From my trip report from last year, here is our rough time line:

Departed from CBO (on Moose Lake) via tow to PP:  7:20 am
Reboarded tow craft after paying fees and completing truck portage: 8:15 am
Arrived at Lincoln Island (adjacent to Washington Island): 9:00 am

We didn't have to spend time actually checking in at the PP Ranger Station because we entered in May prior to the first day reservations are required.  Thus, we only stopped long enough to use the self-service drop box to pay camping fees before we climbed back into the tow boat to make the 50 yard trip to where the truck portage begins. (Paying fees, re-boarding, jump to truck portage couldn't have taken 15 minutes.)

We made a small detour to check out a huge tree (largest diameter in the park area) on the way to Lincoln Ilsand (could have added 5 minutes to transit time between PP and Lincoln Island).

Hope this helps.

dd

From previous trips, I beleive the PP Ranger station opens at 8:00 am.  I've been first in line to clear the check-in before, but by the time I rigged out my canoe and was ready to paddle, it was probably 9:00 am.  I would estimate that approximately 30 people showed up between the time we arrived (7:30ish) and when the ranger station opened--late July/early August time frame.