You don't really need to play h3 (in most lines).
A few things to consider:
1) the f4 bishop is still White's "bad" bishop. Yes, it's outside the pawn chain, but it still has much less scope than White's light-square bishop. So you shouldn't fear it getting traded, if needed.
2) Nh5 misplaces Black's knight (at least temporarily), and White can embarrass it in many lines, like so:
3) The f4 bishop can also be placed on e5, in some lines, to further hamper Black's position, like so:
These are just a few basic ideas to know and build on as you get better with the London. In short, h3 isn't really needed, unless there's a very specific reason to do so. Usually, it's not needed to protect the bishop from the knight.
(The White pawn on e5, especially, is a useful idea to know, as a protected pawn there can really disrupt Black's position.)
hey so i've been playing the londom system for the past 4 months (since i started playing chess basically ) and i'm happy with the results so far 61% win rate and 34% loss rate so far.
one of the rules that i've been following for the past 4 months is to try to keep my dark square bishop at all cost and playing h3 is a way to hide the bishop if the opponent plays Nh5, but after playing h3 opponent plays Bd6 and i can't drop back to g3 since i don't have my pawn on h2 anymore, the thing here is i watch gothamchess and im rosen play trhe london and they neverplay h3, and their opponent never plays Nh5 which is very weird to me.
if someone can explain me why Nh5 is a bad move for black or why they not bother play h3 i'll be grateful