First of all don’t try to trim for the first month at least. Let it grow. If you want to trim, just use a higher number comb and reduce gradually - remember hair grows. The problem if you trim more than required you may make a mistake and end up shaving it all together.
As others pointed out, Beard Oil is a must, don’t shampoo the beard at all, just wash it with water, and maintain it with a beard brush.
I started on my beard since summer last year and never regret it. Takes a while to get the correct style and howto trim but it is worth it. That’s how we were intended to be.
NB: Still go to meetings with full beard, and not a single negative comment mentioned in front of me. Still get the odd looks for old timers.