If you intend on saving any of the birds you get now as breeding stock later on I would go ahead and keep a male for them, it can be harder to introduce one later when you are ready to breed them. However if you don't intend on using these for your breeding stock they don't really need a roo, especially if you don't end up with more than four hens it can really just be stressful for them to have a male kept with them.
You should be fine keeping the babies together until 5-6 weeks no matter your sex ratios, after that if you have way too many roos things can get ugly. However, if you're getting browns this is about the time behavior starts confirming coloration and you can be sure of sex though you'll probably have an idea by 3-4 weeks old once you learn what to look for. If you only have 1 or 2 extra males you may be able to keep everyone together until harvest time for your extra males, especially if you plan on under stocking that 9sqft cage. Keep a close eye as they hit that 5 week mark and if you see chasing or fighting start go ahead and split the males you aren't keeping. Rubbermaid totes are a good idea for temporary housing or brooders too.
Cheers,
Jessie