Just a note. The pulleys aren't vernier adjustable, they're just slotted. This means that they can be slightly fiddly to set accurately, so be careful & patient.
Also, in my experience, most will be different between cylinders & are likely to be some way out, so, as Kev says, if there identical and on the money, then they've been dialled in.
I've always timed using inlet opening (although inlet closing is the most influential timing point), but would say most tuners go with centreline figures. My 'issue' with that is that the centreline does not always correspond with maximum valve lift.
Whatever, get them checked, because it smoothes the bike out and if you play around with the timing a little, you may make a few gains
#33 Racing