May one use a new vessel one time without immersion?
It is a [Biblical] obligation to immerse a food vessel that was purchased from a gentile. One must immerse the vessel prior to using it for food even on a temporary basis [even prior to using it for the first time]. [Hence, unlike the common misconception that a new vessel may be used one time prior to Tevila, there is in truth no allowance to use a new vessel even a single time before immersing it, and this prohibition has consensus amongst the Poskim, and they have vehemently protested the mistaken custom. This applies to all sects of Jewry, whether Ashekanz, Sephard, or Chassidic.] Nonetheless, if one transgressed, and used the vessel prior to immersion, the food nevertheless remains permitted to be eaten. [This applies even if one used it several times prior to immersion.] The above, however, only applies to a permanent vessel, however a disposable vessel, which is manufactured for a single use, does not need to be immersed in a Mikveh prior to use. [Seemingly, this ruling is the cause of the misconception above which erroneously allows using a vessel one time prior to immersion.]
It is forbidden to use a vessel even one time prior to immersion, unlike the common misconception which has no basis in Poskim.
 See Sefer Ohel Yaakov Dinei Tevilas Keilim p. 319; Minchas Shlomo 2:66-14; Hakashrus 4:5; Or Yitzchak 2:17-9; Chayeh Halevi 4:57-9
 Stam opinion in Admur 159:21; 2nd opinion in Admur 323:8 and conclusion of Admur there “The main opinion follows that Tevilas Keilim is Biblical, as explained in Yoreh Deah ibid”; Implication of Michaber 320:9 and 14 and 17 who rules a Katan is not believed; Taz 120:16; Peri Chadash 120:1 [see there in length]; Rashba in Teshuvah; Raavad; First option in Ramban on Avoda Zara 75b; Ritva on Avoda Zara ibid in name of Ramban that it is Biblical; Rashi Avoda Zara 75b; Tosafus Avoda Zara ibid; Rabbienu Tam Yuma 78Semak 199; Issur Viheter 58:91; Aruch Hashulchan 120:4 that so agree majority of Poskim
Other opinions: Some Poskim rule the Mitzvah of immersing vessels is a Rabbinical obligation. [1st opinion in Admur 323:8; Rambam Machalos Assuros 17:5, as understood by Rashba in Toras Habayis p. 155 and Peri Chadash ibid [however see Rashba in Teshuvah ibid and Aruch Hashulchan 120:1-3 for alternative understanding in Rambam]; Leaning explanation of Ramban Al Hatorah Matos and second option in Ramban on Avoda Zara 75b; However see Ritva on Avopda Zara ibid in name of Ramban that it is Biblical; Ran; Ritva; Or Zarua 1:359; Radbaz 34 that so rule majority of Poskim; Yeshuos Yaakov O.C. 509:4]
 Michaber Y.D. 120:1; Mishneh Avoda Zara 75
 Rav SZ”A in Minchas Shlomo 2:66-14; Hakashrus 4:5; Or Yitzchak 2:17-9; Chayeh Halevi 4:57-9; Ohel Yaakov ibid; Pashut as the Poskim make no mention of such an allowance. It is not mentioned in any of the discussions of what should be done if a Mikveh is not available, or if it is Shabbos and one cannot immerse the vessel [see Michaber Y.D. 120:16 and Admur 323:8 regarding Shabbos; Rama 120:16 regarding during the week in an area without a Mikveh; Mordechai Beitza Reemes 677] It is also not mentioned amongst the reasons of why we rule disposable vessels do not require immersion. [Maharil Diskin Kuntrus Acharon 136 [regarding if food is already in vessel]; Chelkas Yaakov 2:47; Minchas Yitzchak 5:32; Igros Moshe 2:40; Rav SZ”A in SSH”K 9 footnote 41; Rav Yaakov Yosef Za”l; See Hakashrus 1:34 and 4:23] Chazon Ovadia Shabbos 2 p. 38] and there is also no logical reason to allow a first-time use; so is also proven from the Rama Y.D. 120:8 who goes even further and rules “However, the first person is prohibited from using the vessel for the need of a meal even temporarily without immersion.” Thus, showing that not only is a first-time use forbidden but it is even forbidden if one only plans to use the vessel one time and then sell it to another! Now, although the Aruch Hashulchan 120:41 explains that even accoridng to the Rama ibid, it is permitted to use it a on occasion, this refers to the case of the Rama ibid where the vessel was not purchased for purposes of food, however, if the vessel was purchased for food purposes, no one holds that it can be used even one time prior to immersing. [Minchas Shlomo ibid]
 Rama Y.D. 120:8 “The first person is prohibited from using the vessel for the need of a meal even temporarily without immersion.”; See Aruch Hashulchan and Minchas Shlomo in previous footnote
 See Ohel Yaakov ibid; Or Yitzchak ibid
 Rama 120:16
 Maharil Diskin Kuntrus Acharon 136 [regarding if food is already in vessel]; Chelkas Yaakov 2:47; Minchas Yitzchak 5:32; Igros Moshe 2:40; Rav SZ”A in SSH”K 9 footnote 41; Rav Yaakov Yosef Za”l; See Hakashrus 1:34 and 4:23
The reason: As by wine and coffee, the food is already in the vessel, and the laws of immersion do not require one to remove the food. [Maharil Diskin ibid] Furthermore, only permanent vessels require immersion as according to some Poskim [Shev Yaakov 31, brought in Yad Efraim 120] the obligation of immersing vessels is dependent on if the vessel is Mikabel Tuma, and a temporary vessel that one plans to discard is not Mikabel Tuma. [Chelkas Yaakov ibid and Minchas Yitzchak ibid, based on Rambam Keilim 5:7] In addition, even according to those Poskim [Mahariy Asad 216; Gidulei Taharah 17] who rule that immersion of vessels is not dependent on their status of Kabalas Tuma, the Sages only established the Mitzvah of immersion to meal vessels, and a vessel that does not have a continued use is not considered a meal vessel. [Minchas Yitzchak ibid, based on Gidulei Taharah ibid]
Other opinions: Some Poskim rule that aluminum baking pans and the like need to be immersed prior to use, and hence should preferabbly only be purchased from a Jewish owned company. [Chazon Ovadia Shabbos 2 p. 38]