How does one calculate the end of the eleven months for Kaddish-from the time of death or the time of burial?^[1]

Some Poskim^[2] rule that the eleven months of Kaddish is counted from the day of burial. Other Poskim^[3] rule it is counted from the day of the death. Practically, one is to follow the day of death.^[4]  

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[1] See Igros Kodesh 3:199; 4:107 [published in Shulchan Menachem 5:292-295]; Gesher Hachaim 30:9-10; Nitei Gavriel 51:4 footnote 6-8; Pnei Baruch 34:9; Yabia Omer 5 Y.D. 32; 7:43-10; Yalkut Yosef Aveilus 40:4

Background:

There is known dispute regarding whether the 12 months of Aveilus is counted from the day of death/burial, and whether the Yahrzeit is the day of death or burial, and whether the 12 months in Gehinnom is counted from the day of death or burial. It is possible to learn that regarding Kaddish there is a similar dispute, as depending on when the 12 months of Gehinnom concludes would depend on when to conclude Kaddish [see Kneses Yechezkal 47]; On the other hand perhaps it depends on the start date of the Kaddish, whether one started the day of burial or the day of death [see Daas Torah 376:6].

[2] Implication of Shach 402 in Nekudos Hakesef that Mishpat Reshaim of 12 months begins from day of burial [see Kneses Yechezkal 47]; Levush brought in Elya Raba 132:4; Noam Megadim 1; Kitzur SHU”A 26:17; Neharei Afarsimon 97; Biur Halacha 132; See Daas Kedoshim 377; Levushei Mordechai 223

[3] Implication of Taz 568:4 that Mishpat Reshaim of 12 months begins from day of death; Beir Heiytiv 132:5; Siddur Yaavetz 39 [see Nitei Gavriel ibid footnote 6]; Kneses Yechezkal 47; Mateh Ephraim 4:1; Alef Lamateh Kaddish Yasom 3:5

[4] Igros Kodesh 4:107; Custom of Rebbe Rayatz as brought in Reshimos Hayoman p. 416 [However, see Igros Kodesh 3:199 that the Rebbe directed the asker to follow the day of burial and not the day of death! See also Igros Kodesh 13:410 in which the Rebbe implies to follow the day of the burial. Vetzaruch Iyun!]; Yabia Omer ibid; Yalkut Yosef ibid

The reason: As Admur 71:1 rules to begin saying Kaddish the day of death and according to some Poskim [see Daas Torah ibid] the dispute is dependent on this matter.