How to visit Pena Palace

I'm confused about how the visit to Pena Palace works. I was hoping to visit either first thing in the morning OR later in the day at around 4:30pm once crowds have gone down. I was reading another thread that said it is still very crowded at 4:30pm and the interior of the palace was like a shuffle through the rooms. The morning tickets are currently sold out online on the days I'd like to visit. Can I stand in line first thing before 9am on the morning that I want to visit, or can only those who reserved advance tickets enter the palace? Also, how do the timed tickets work? Can I enter the grounds around the palace prior to my timed ticket and then stand in line to enter the interior palace at the time of my ticket, or do you have to visit the palace first then walk around the grounds? If I reserve a later ticket, say 5 or 5:30pm, I want to be sure I also have enough time to walk around the exterior grounds as well before they close at 6:30pm.