Eating on Erev Yom Tov:
The general rule: It is a Mitzvah to refrain from beginning a meal past the 10th hour of Erev Yom Tov, just as is the law regarding Erev Shabbos. This is in order so one be able to eat the Yom Tov meal with an appetite, as eating the meal with a proper appetite is included within the Mitzvah of Kavod Yom Tov. [On Erev Sukkos and Erev Pesach it is not merely a Mitzvah to refrain from eating past the 10th hour but it is an actual prohibition to eat a meal, as will be explained.]
May one eat a meal past the 10th hour if he did not eat prior? If one transgressed or forgot and did not eat prior to the 10th hour, then he may eat a meal past the 10th hour [with exception to Erev Pesach and Erev Sukkos].
May one eat past the 10th hour on the first day of Yom Tov: On the first day of a two day Yom Tov, as occurs by all Yomim Tovim in the Diaspora, and on Rosh Hashana in Israel, one is to begin the Yom Tov meal of the first day prior to the 10th hour in order so one have an appetite to eat the night meal of the second day of Yom Tov. If one did not begin before this time he is to eat the meal even past the 10th hour.
 The Rama however states that it is forbidden just like on Erev Shabbos. Vetzaruch Iyun Gadol as by Erev Shabbos itself it is only a Mitzvah and not an obligation. The Mishneh Berurah [529/5] thus concludes that this wording is inaccurate and it really intends to say “a Mitzvah”. To note however that also the Magen Avraham [668/1] rules that it is forbidden to eat past Mincha of Erev Shemini Atzeres. Vetzaruch Iyun
 This is due to an explicit teaching that we have for Erev Pesach and Erev Sukkos which teach that it is forbidden to set a meal past the tenth hour.
 Hoshana Raba
 471/1-2 regarding Erev Pesach; 639/20 regarding Erev Sukkos
 Regarding Erev Sukkos Admur writes “Min Hamincha Ulimalah” which seemingly refers to Mincha Ketana of which we do not eat “Samuch Limincha” which refers to the 10th hour. This explanation that “Min Hamincha” refers to 10th hour is found in Rama 529 which rules that it is forbidden to eat Erev Yom Tov from “Hamincha Ulimala” and the Magen Avraham explains this to refer to the 10th hour and so rules Admur simply [there in 529]. However Tzaruch Iyun as for why Admur here did not also just simply state the 10th hour, as he does there in 529/2, and especially in light of fact that in all the Halachas mentioned of not eating on Erev Chag/Shabbos Admur mentions specifically the 10th hour. [249/9 regarding Erev Shabbos; 471/1-2 regarding Erev Pesach, and 529/2 regarding Erev Yom Tov.]. As well the question intensifies over the fact that the Rama rules it is forbidden from Chatzos and seemingly if Admur were trying to argue on the Rama he should have stated clearly without doubt of its meaning that he holds its from the 10th hour. Thus although we find a source for ruling that Min Hamincha refers to 10th hour, it is puzzling why Admur did not just state this explicitly. Vetzaruch Iyun.
In other Poskim:
Rama 639/3: The Rama rules it is forbidden to eat a meal from midday of Erev Sukkos just as is the law on Erev Pesach.
Magen Avraham 639/12: Asks on Rama that on Erev Pesach it is only forbidden to start a meal from the 10th hour. He answers that bread [which one cannot eat on Erev Pesach] is more filling than other foods, and thus bread which can be eaten on Erev Sukkos we are more stringent and forbid it from midday. However he concludes with asking a) what is the source for such a differentiation, and b) why does the Rama conclude as explained in the laws of Pesach. He thus concludes with a Tzaruch Iyun. Some [Kaf Hachayim 639] learn the Magen Avraham’s final stance is to be arguing on the Rama that even bread is only forbidden from after the 10th hour, and others [Kitzur Shulchan Aruch/Chayeh Adam] learn him to accept the differentiation that he made between bread and other foods.
Gr”a 639: From 10th hour. Says Rama holds like Rishonim which forbid eating form midday, but that is not how we rule as explained in Hilchos Pesach that we rule it may be eaten until 10th.
Chok Yaakov: Argues on differentiation of Magen Avraham and rather explains that Rama always holds even by Pesach that the prohibition to eat Mezonos or Hamotzi foods begin from midday, and it is just because that eating Mezonos/Hamotzi on Erev Pesach is not done being that we do not eat Matza Ashira anymore, that the Rama did not say so in Hilchos Pesach. [Based on this explanation it is evident that Admur clearly does not rule like Rama being that he clearly states in 471/1-2 that Matzah Ashirah may be eaten on Erev Pesach until the 10th hour, which according to the Chok Yaakov’s explanation of the Rama is incorrect.]
Kitzur Shulchan Aruch: Rules that bread may not be eaten from midday while other foods from 10th, and sources it in Magen Avraham.
Chayeh Adam: Rules that bread may not be eaten from midday while other foods from 10th, and sources it in Magen Avraham.
Mishneh Berurah 639: Rules that the Achronim have agreed that it is only forbidden from the 10th hour.
Kaf Hachayim 639: Brings that the Magen Avraham and Admur argue on Rama and the restriction begins from the 10th hour. Although he himself brings other opinions.
Mateh Efrayim [625/7] : One is to eat his meal prior to midday, although if one did not yet eat he may nevertheless eat a meal until the 10th hour.