especially now that they've had two years of separate training they all deserve breathing space so we can get back to knowing them again.
Given that, I think delaying the new member much more is not a bad thing.
I think it's quite the opposite.
IMO Enies Lobby gave us much more interaction, insight and development of the SHs, than Skypiea and Davy Back Fight combined.
(as well as 3 members joining/rejoining the SHs)
So what we need is another hectic, complex, chasing arc like Water7+Enies Lobby, and the next 15 chapters or so should be enough for us to relax and enjoy the simple pirate life, before things get serious again, just like with Skypiea and Water7.
Also imo there is no way, that the future Pirate King can cross the Red Line and continue through the New World, without first paying a visit to Mariejois and being part of a major ruckus there. (just like with Enies Lobby, Impel Down and Marineford)
And it seems obvious to me, that we will get a repeat of the Fisher Tiger incident, only on a much bigger scale.
That could set things up very nicely for the chase through the New World, introduce Luffy to his farther finally, give plenty of room for insight and development of the new SHs, and find us a few new awesome Nakama. (maybe Bonney and the son of Fisher Tiger)