I'm pretty sure once you're done with your FPP's for that day and they disappear from your screen on
MDE that you can book for the next day. Usually mine will show for a few minutes after I scan at a ride but by the time I get off the ride it's no longer visible on MDE. I don't use GLFP that much as described in the first post so I'll wait for
@ScrapYap to chime in too but I know it works that way for AP. So if I have 7 days booked (the maximum I'm allowed), once I'm done using any FPP's I want that day (remember if you're going to try to get a 4th & subsequent you'll need to wait until scanning the last one) I make sure everything is gone (and just cancel any that remain although usually I get an error message if I try to do so and then they're gone when I refresh) and can book another day's worth at that point.