Bathroom Revamp: Any Advice

As an interior designer, i've seen bathroom remodels take 6 months! That can happen when you are going ultra custom- lots of delays and long lead times.
Make sure you have everything selected, whoever is purchasing should be checking stock and lead times to prevent unexpected delays or need for reselection. Especially on things like tile. You want to make sure nothing in your specifications is on back order, discontinued.
If possible order everything and have it warehoused before you even start demo.

I have been through a MAJOR reconstruction with three kids. You don't need to buy a commode. I doubt you and your son will need to use the toilet more than a few times in the afternoon, and trust me these guys are used to kids and interruptions, it's part of the job!
You may find this to actually be kind of fun for your son. My contractor (who is also a close family friend) gave my kids all kinds of "jobs" during our project, they especially liked the demo phase. There's nothing quite like the look on a kid's face when you hand him a hammer and tell him to smash something LOL! Just make sure he's got some safety goggles on first :-)

You can rent an outhouse like they do on construction sites. The company comes and cleans it out once a week. Yes, it's outside but at least you have someplace to go when you need to.

Your water will probably be turned off for periods during construction. It might be handy to have some bottled water set aside to drink, cook and wash hands when that happens.

Not sure what else you need but we just had our bathroom redone (new floor, tiles on the walls, new paint) and while it was only 1 guy, our entire bathroom was out of commission for 3 weeks (one of them being Thanksgiving). So I'd plan on being out 2 weeks at least unless they said shorter.

I'd plan on not being home in the afternoon...or do you have a portable potty for the kid(s)? You can always hold it and go to the store/library/etc but kids can't!

Congrats on the new bathroom! That's awesome!

I will suggest that when you get it repainted, have them put a coat of Killz on first. It protects the walls from moisture damage and keeps paint from bubbling up. Also, if there isn't already a really good fan in there, have them put one in.

It shouldn't take but a few days until they're done. Consider a 5-gallon bucket lined with a black trash bag with "Feline Pine" kitty litter inside as your temporary toilet. Put your toilet seat on top. Too easy.

When we had our bathroom gutted a years back, our guy (family friend) made sure we weren't without the shower every morning. Dear thing, he even re-hung our rod/shower curtain every night! Lol
But we were kidless then. I can see that the toilet use will be a slight issue.
I'd just have them take a break when he needs to go! Lol
Personally, I think EOD I'd hit s library, friend, Grammy, etc.
It will be so worth it!

If it were me, I'd fashion bucket into a port-a-potty, and use some flushable cat litter in it, to help keep smells down, and have that available in the make shift bathroom. Here are some links, but I'm sure there are a ton more out there.
http://www.family-survival-planning.com/portable-toilet-f...
http://flushablecatlitter.net/

Of course, it depends on your gross-out factor whether you (or family) can handle this. IMO, it's better to have access to something (even primitive by today's standards, but still function) then not.... but I'm not really grossed out by body functions....

go out to the library for a few hours or the mall, or local nature centers with indoor areas? make it fun to try not to be in the house?

all of those places have bathrooms too