All depends on the size of the growth/fan leaves. My plants at present I topped them just the other day at 3rd node, I left the fan leaves on and today with fan leaves still on I made the 2nd cut still with fan leaves attached.
I still haven't pinned them back yet to create my hub, probably ill do that in 2 or 3 days time from now and I'll cut fan Leaves off then.
In my experience with main lining it all depends on what strain you using, some grow faster than others . I usually wait till the new mains fan leaves about 2 to 3 inches before removing older fan leaves to then pin her down to create the hub.