fastpass strategy

My 30 day window opens in a couple days and I’m wondering about strategy. Is it best to book the rides you want regardless of times (and refresh to change the times), or book what you can earlier in the day and try to modify to different rides or snag 4th/additional FPs day of in the park? I...

We are going to MK for one afternoon as a cruise ship excursion in March 2020 for a party of 4. My estimates on time is 1:15 to 7:30. Fastpasses: 1:30 - Space Moutain, 2:30 - Jungle Cruise, 3:30 - Peter Pan's Flight (will this be too difficult to get 30 days out?) 1:15 - Laugh Floor Space...