Stray kitty

A stray kitty started coming around about a week ago. I've been feeding it, and I don't think I'm the only one. It's the smallest of all the strays and other cats will try to fight him if they see him so he stays on my porch as often as he can. Problem is, I'm not allowed to have pets 😅 so I called a no kill animal shelter about an hour away from me and they have a spot for him but I can't bring him until Friday. Until then, what should I be doing for him? I haven't had a pet for a long time and I've always said I won't get one until I can afford any all all expenses that come with having one, which I currently cannot. I got him cat food (meow mix tender centers) but I'm sure there's a better kind for him. He has a weirdly round belly (thought it was a pregnant girl at first until I looked) and Google tells me it's a sign of worms. Should I get dewormer now or should I wait and let the shelter determine what medical help he needs?