I'm on the record (more than once) as thinking that D&D 3.5e's experience system is "a work of sublime genius", and I stand by that. But I don't think that this carries over to Pathfinder.
You see, the main genius about experience is that it catches people up when they fall behind. 3.5e provides many ways to fall behind: death (and being resurrected by any means other than true resurrection), spending XP on crafting magic items, casting powerful spells with an XP component, being level drained, and the obvious missing a session.
But in Pathfinder, only one of those applies. They changed level drain so you just keep a permanent negative level instead of ever losing a level. They changed death so that it just gives you permanent negative levels instead of taking away a level. They changed crafting and spells so they cost more gold and never cost XP. The only one that applies is missing a session (and I'm lucky enough to be in a group where people hardly ever miss sessions, and if one person is going to miss a session, we don't play Pathfinder, though sometimes we'll play something else).
This is why, when called upon to run a Pathfinder game some time ago, I decided -- blasphemously! -- not to use the experience system at all. Which happened to be what the group was used to -- we'd just played through Rise of the Runelords without experience, leveling up only when the adventure path said we should, and it worked out fine.
How, then, do I determine when the players ought to level up? Well, I take as my baseline the line from 3.5e's Dungeon Master's Guide (page 41, Behind the Curtain: Experience Points sidebar) that experience "is based on the concept that 13.33 encounters of an EL equal to the player characters' level allow them to gain a level". So if I'm stripping out XP, I can just go straight back to that baseline. (I don't know what Pathfinder's experience guidelines are based on, especially because there's three different experience tracks to muddy the issue, is why I go back to 3.5.) To wit: players should level up once every 13.33 encounters.
Except I round up to 14, which more readily divides in two. It's become my habit to prepare 7 encounters at a time, which the party generally gets through in one or two sessions, leading them to level up once every 2 or 3 sessions. You can, of course, use a higher or lower number than 14 if you want your players to level up more or less frequently.
You can get fancy -- a particularly easy encounter counts as 1/2 an encounter, a particularly difficult encounter as two. You can choose to count encounters that the party bypasses entirely, or not count them, or count them as half. What matters is you pick an "every X encounters, the party levels up" and then mostly give them encounters appropriate to their level.