When it is a clean as I can get it, I immediately peel the tape. This sealant can be messy and you want to have plenty of rags or paper towels and solvent available. The tape will have sealant on it and anything it touches will too! This is what the joint looks like after the tape is peeled. Resist the temptation to further tool or smooth the joint! You will only make things worse at this point. Note that I do not have the "finger fillet" so common to these kinds of joints. This thin tail of sealant does no good for anything in my opinion, and is most often the first point of failure as it peels up. The sealant that is doing the work is between the flange and the roof:
The completed install. I would guarantee no leaks on this without any maintenance for 10 years, and would be very surprised if it leaked in 20 years:
In contrast the factory installed Fantastic vent just aft of this one already after 4 years has nearly total failure of the secondary sealant smeared on top, the black cracks are due to dirty and water collecting in the failed sealant. It doesn't leak yet but will be a mess to clean up and do right:
