To get the best flower show, I cut the wispy tips of the branches down to the uppermost robust looking buds/nodes as soon as it starts leafing out. Cut back floppy branches to a more sturdy point. Don't cut more than this before flowering so you don't lose your show of flowers this year. Not a huge fan of e-how but these particular instructions are good.

Someone closer to your area would better answer the question about when to separate the babies but in general, you need to have a place ready for them to go, it's not too hot yet, and you won't be going on some long vacation. Extra shade for a few days after separation (I love lawn chairs for this) if you find them wilting.

Excellent! Thank you!
And not a moment too soon - they are leafing out now!
Thank you for responding!

You're welcome :)