My guys are grown now. When they were small and I packed their school lunch every morning, one of them was hung up on bologna on bread - plain and dry. At first I spoiled him by cutting off the crust, just because he thought it was best that way. Then I got out some cookie cutters and started punching out star shaped sandwiches and so on. I also free handed specials, like a pumpkin with the eyes and mouth trimmed out.
His friends at lunch were always waiting to see what he would pull out each day, and I got used to eating the left over trimmings as I made the sandwiches. Of course it would probably work with peanut butter and jelly also.
Or maybe try making some Mickey Mouse pancakes. Two little round ear pancakes poured next to a large round head pancake. Make face with chocolate chips or syrup, cherries, whip cream, etc. Of course it could be easier to find a cafe willing to make those for both of you.
In whatever you do, consider being prepared to take candid photos of your beautiful son to frame around the new house ... wonderful new memories. Maybe your mom would enjoy taking some of you two together.
If you get a house we can all share ideas on decorating bedrooms for special little boys. As a matter of fact, I think I recall Jack3B describing a jungle theme he did. Or maybe that was his room?
Good luck to you on making your time with your son unforgettable for both of you.