It depends on a number of things. Do you have a car? Will you be traveling a lot because if so you need to consider money for gas. Are you paying utilities? Rent is a lot lower lets say on Lakewood than Queens. Do you have any bills /debts to pay off? 2/2500 seems OK, but little things do come up. Having a little extra for those nights when you just want to go out to dinner, or away for the weekend is really nice to have. But if
Your rent in in the 1000,1200 range that should be ok. Don’t buy a brisket to make every shabbos if things ate tight. Also buying family packs of chicken I have found saves money and I freeze what I don’t use right away and use if for week night dinner or the next shabbos.
Also find out of your grocery gives discounts. In queens the grocery stores give discounts if you are a teacher or if you are in landers.
Good luck!!