Question about Boss Battle

[Lib Feathers]

I've seen stage 1 - how many stages are there? Do you have to complete them all at once or can you do it at different times without having to start at the beginning? I'm not usually online more than an hour or so, so I was wondering if I can do it a bit at a time or should I wait till a day when I have plenty of time?

I suppose no one can "go to" you when you're in the battle, either, so they're listed as online but you can't teleport to them the whole time.