The post OCS timeline will always vary. It just all depends on how the student track is going. Back when I went through (early 2015), the SNAs went to OHARP for a month or two and the SNFOs were checking in to NASC that following week. I was still stashed in A-Pool for about 2 months before classing up for IFS, but after that everything went pretty quickly. I had about 2 weeks between IFS-API. After API, I had about a good month or so before starting Primary. After Primary we all branch off to whatever advanced track you may have selected so it all varies after that.
Again, I think it all boils down to the student track all through the pipeline. If Primary is way backed up then I'm sure that they may slow down the class up times for IFS/API just to help out the wings/squadrons.
My info is a little dated as many things might have changed. Its always a crap shoot. Regardless, enjoy every free minute you have after OCS because its the only small bit of time where you will have ZERO responsibility. Once training starts, it NEVER stops!