How long to wait before grafting Pereskiopsis?

Hi everyone,
I have a whole bunch of brilliant Pereskiopsis cuttings all potted up only a couple of days ago, so though I haven't checked (don't want to bother them too much), assume they haven't begun to root yet. So I have a two part question for you guys...

I've read it should be about ten to fourteen days before they root (kept indoors with good filtered light) does this seem about right?

How long after they have taken root can I begin to graft onto these Pereskiopsis?

Thanks guys, sorry to drag up old questions, I'm just really exited about getting into this and want to do it right.  

I start grafting 1 week after potted up cuttings.
I believe it does not matter rooted or not rooted stocks for the grafting.
1 week after the grafting, I repot stocks with scions.
I can see roots on almost all stocks at that time, 2 weeks after potting up.

When roots of stock have started to develop, the grafted scion also starts to grow.

Yes I have done grafts with and without roots and both work just fine. I find you can save a bit of time by using cuttings without roots, burying them about 1/3 in growing medium and then grafting right away. I try and use cuttings about 20cm in length.

Great,
thanks for the advice guys, much appreciated.

I'll keep you posted on how everything goes.