There’s a mitzva to go into Shabbos with some hunger. Therefore, one is not supposed to have a large meal on Erev Shabbos.
A Seuda that’s a mitzva can be eaten on Erev Shabbos.
In all situations, no matter when the meal started, one has to stop eating and drinking at sunset. Eating can resume after kiddush.
There are Three options when to make the Seuda:
Best: wash before midday, Approximately 12:10 pm in NY.
Good: wash before nine hours into the day. In NY, it’s either at 2:55 pm or 3:30 pm depending on the opinion.
If necessary: wash until sunset but don’t eat too much bread
In all of the above scenarios, if you’re in the middle of the meal and Shabbos comes in (sunset) and you want to continue eating:
1) cover over the bread that’s on the table.
2) pour a new cup of wine.
3) make the kiddush for Friday night but without making the Bracha of borei pri hagafen (unless you haven’t had wine at the meal).
4) eat an eggs worth of bread.
5) continue the meal.
6) if no bread was eaten past a half hour after sunset then Ritzei shouldn’t be said and just say Al Hanisim.
7) if bread was eaten past a half hour after sunset then say Ritzei but only say Al Hanisim at the end of the Horachaman’s and not in its proper place.
8) Kabolas Shabbos can be said whenever you want.
9) Don’t forget to daven maariv This process is called ומקדשמפהפורס which means, covering the bread and making kiddush in the middle of a meal.
In all of the above, if one davened maariv in the middle of the meal then Al Hanisim can no longer be said.