Hi cheesey, the time skips thing is really hard to do, so don't beat yourself up about it. We've all read fine, fine stories where there's a rapid spanking that turns into a fucking that turns into a fisting, and then the passage ends with "... and he kept doing that to me all night."
My advice would be: don't write yourself into a corner. I've half-written many stories myself that are intended to involve training over weeks and months, yet which fizzled out after a day or two... because you can do a lot in a day or two. Hehe. For a long while, I only wrote stories that lasted for an evening, and even with that limitation, some of those were pretty long.
So, if there's a punishment scene (for instance), don't say that it's going to last for a week when you only have a day's worth of juicy material (four or five little scenes, perhaps, dotted throughout the day). I'm sure you can make that day pretty torrid.
Good luck. The world needs more perverts who want to write better.
Q