I'm hoping there'll be a date at the end of the episode.
Don't hold your breath. If it were the case I think we'd know about it.
You mean the sentence when the Beast of Darkness tells to Guts that its power will be restrained until the chains will be broken?
Yes. Not really a conversation, more of a monologue. Not to mention that Guts couldn't remember what the dream was about.
I'm also a bit surprised to see Guts making use of the armors power. It looked like he had things under control, for the most part.
Yeah... It strikes me as pretty similar to what happened when all the Makara showed up in volume 31. An overwhelming challenge appears and he instantly resorts to the armor without trying to fight without it first. It's a worrying pattern for him, because it's much too dangerous to be relied upon like that (as Farnese reminded him in episode 314).
If Guts loses himself, again, to the armor it may be up to Farnese to give a rescue a try. Good thing Schierke taught her how to have an out of body experience. Something tells me Farnese isn't quite ready to go in and rescue Guts' ego.
Yeah, it seems too early for Farnese to try something like that. Besides, Schierke should be able to get to him in her astral form even from a distance. It might be more difficult, but they're not
that far away.
Maybe we're not giving Guts enough credit, maybe he can pull himself out. If he wants to prove something, then pulling himself out of the armor's influence would be something to prove.
Honestly I don't see him dominating the armor's effects on his own at this point. But since the Beast is laying low, he might have an easier time getting back to his senses, which would eventually lead him to a false sense of security with the armor ("It's getting easier to control it!"). Very dangerous in the long run.
Nothing's done at this point though. It's all a matter of whether the armor can overpower its wearer's mind even when he's (more or less) at peace. For all we know the worst could happen. The nameless guys accompanying Roderick might not make it back to the ship for example.
Also, I'm doubting whether or not
is even capable of rescuing Guts' ego.
Yeah, nothing in the manga suggests that the Skull Knight is capable of such a feat.
Now it's possible the Beast will voluntarily relinquish his hold on Guts after all the nasties have been slain. But why would he?
You should be careful not to always equate the Berserk's armor with the Beast of Darkness. It's the armor that is blinding Guts in that case, fanning the flames of his fear, rage, hatred, etc. while obscuring the rest. It's what it does, how it works.
Because the Beast of Darkness is a psychological character representing a certain part of Guts it can be hard to know how to interpret its attitude, but maybe what it said in episode 290 implies that Guts will be less receptive to the armor's Od and less likely to blindly kill his friends without even realizing what he's doing. Or maybe not.

things would be IMHO much more interesting if the Beast stays an uncontrollable thing for now. 
Of course, but on the other hand it's not the first time they're in this situation. So far it's nothing new, just different monsters.
At least I hope to see Guts destroy the ship while the effects are there, and see the real shape of this creature.
I have to admit I'm dying to see what it is. The damn thing's been eluding us for almost a year now!