You would be the best judge, since you know him best.
Would he really sit still for 3-ish hours of painful back combing?
Palm rolling does nothing except make dreads look neat for a few hrs short term. If done for a long time, it can cause serious damage to the hair. Baba Fats posted a video about rolling damage. Clean hair dreads.
Going 3 months with out a wash is just.....gross. Especially on a 4 hr old, they are dirty little buggers as is.
Dreads (new and old) should be washed 1-3 times a week. Clean dreads are happy dreads.
Rubber bands are painful, goofy looking (think SideShow Bob, Coolio, Snoop Dog), can melt into the dread, rot into dreads, cause weakness and breakage. Plus more...rubber bands are just bad.
Separating dreads can be painful, if they're left to congo uncontrollably. Once or twice a week (preferably when his hair is wet) sit down with him, read a book or something, and go thru his hair. It doesn't have to vicious, just gentle pulling apart of hairs. He might even enjoy the closeness of it, bonding.
Wax is satan re-incarnated in an inanimate substance.
Honestly, and this is just my opinion...with the texture and curls of his hair, it'd for some of the most beautiful natural locs ever. Curly hair like that sections like, instantly. Because he's so young, he's probably pretty active so it's going to move around and tangle up quickly. I don't think he'd look neglected at all. Besides, he's your son. If you're very worried about it, I'll knit him a little tam to wear in public!