In the #121: The Lost Outpost, the adventure notes specifically mention that that the GM can request a "wish list" from their players, especially for magic items they'll want in the future, so that they can be seeded in loot drops.
The only trouble is, when dealing with players who either aren't familiar with Pathfinder specifically, are playing a class that they're not incredibly familiar with for the first time, or with the concept of tabletop RPGs, how would they know which magic items they would need at later levels?
As for crafting times, I've seen a few places so far in the first two books where the adventure says, "There's a gap of a couple weeks, which is good for crafting". And then there are at least two NPCs (the alchemist and the blacksmith) who could probably make things, provided the PCs made sure to be on good relations with them.
Just my $0.02.