Going west, the best time would be either roughly 9am to about noon, or 1pm to about 2:30 or 3pm. Traffic will still probably jam up right by downtown (it's a horrible "squiggle" of a road), and again coming up to I-610 (just lots of cars period). It might slow up a bit close to Beltway 8 also, but usually not quite as bad.
Also keep in mind that one incident (wreck or whatever) could lay waste to any of this. It doesn't take much for people to get stupid here.
I would not do 105 only because of Conroe. The traffic is just too bad through there these days, even if you took loop 336 around, though if you did decide that, you would definitely want to take that loop around (going north around the loop would be better). And again, one wreck, especially as you got closer to Conroe would render all the above null and void.
Good luck.