I decided this run to specialize in a few weapons. As soon as possible i had my mage take crafting to enchant a few bows. the rest of the party leveled up before the enchanter. a few fights later, because of CR adjust, my lower level enchanter has more XP than the rest of the party. you can use CR XP bonuses to even out enchanting XP costs until level 10.
Yes, if you are going to craft, you should craft as soon as possible (if you wait until after 10th, you won't be able to catch up). And as many have noticed, if you wait to level-up until you are just shy of the next level, you'll gain more XP (at least until 10th level). I generally level-up my non-crafters immediately and let my crafters wait until they are about to reach the max XP mark. NOTE: This trick won't work nearly as well if you have much higher-level NPCs. So if your 3rd/4th-level party recruits Otis or Thrommel, the 3rd-level and 4th-level characters will gain very similar XPs.