It's hard to say when or if he will completely go to sleep, beardies are kind of like people in that sense, because it really depends on each individual dragon and what they think their body needs. I have heard some stories here where users' beardies have slept for 3 months straight without waking up (even for baths), some that sleep on and off for just a couple of weeks, and some that don't even brumate at all, or decide to start years later.
I would give your beardie something he can hide in, even a small cardboard box with a hole cut into one side that he can fit into would work great.
He may be staying awake because there's nowhere he can hide, because his instincts would be telling him that he can't just fall asleep out in the open, in case of "predators." Just make sure you put the hide on the cool side of his tank, they usually look for cooler places to sleep when brumating. I would keep
bathing him every day or two until he empties out his system, and then see what he chooses to do. If he stays awake you should keep offering him food every day, but he may not eat it. If he does eat you need to make sure he stays awake long enough to pass it through again. If he fully goes to sleep you can just keep an eye on him, and give him a
bath at least once a week.
Here's a little rundown on what has been happening with Doodles' first brumation, just to give you an idea of things you could do, & things your beardie might do:
Back at the beginning of October, Doodles started getting really lazy & was spending a lot of time just lounging on the bottom of her warm side, giving me the stinkeye. She was eating less & didn't really want to be taken out of her tank. I made her a hide with a small USPS box, it's big enough that she can curl her whole body into it, but there's not a ton of extra space, so she feels secure. I threw a hand towel in there too, so she can cover herself up or lay on something soft. After the hide was in her tank for about 3 days, I woke up one morning to find her face first in the corner of the box, burrowed underneath her towel. She stayed there for a week, until I woke her up for a 20 minute
bath. After that I offered her some worms, she refused them, and was back in her hide by the next morning. That has pretty much been the weekly routine since then. Once, she changed her sleeping place, and slept under this stone corner staircase thing she has for a week, and a few days ago she ate some worms, so I've given her a
bath every day since so she can pass them before she goes back to sleep. She's still awake for now, I'm sure after she poos she'll go back to sleep though.
I hope that helps, and at least gives you a little bit of an idea of what you can expect with Zeus. There's also a great article on brumation on this site, I read it when Doodles first started getting sluggish. Here's the link to that, just in case you haven't seen it and would like to take a look, it's got some really helpful info
http://www.beardeddragon.org/articles/brumation/