(I’m channeling my own lawyer here - I had a similar situation and this is how he analyzed it):
If phase 2 is eight hours on Saturdays, but he never makes it to 8 hours, then he’s not exercising his access. You move to phase 3 after 60 days of exercising access, not after 60 days of being entitled to exercise access. This holds true as long as you are not doing anything to prevent him from exercising access, and it sounds like you aren’t. So - if he successfully exercises his entitled access for 60 days, that’s great, next step is phase 3. But if he is picking up the kids and dropping them a few hours later, he is not doing what he needs to do in order to progress along the phases you have agreed on.