Grafting- changing clothes

Hello all,
In 2008 a successfully collect an old eastern white pine. I slowly worked down it's root ball and it has been in a bonsai pot for the last three years and growing incredibly well every year since collection. I decided to finally try my hand at grafting to change the foliage which was very far away from the main trunk and normal long white pine needles to a dwarf variety of eastern white pine. I did five grafts and four look like they have taken and are pushing a new candles. Im wondering if and when I should be cutting off the parent foliage, and if it should be done slowly over time, or all at once? I can't find anything to help me with this question.
Thanks

I'd wait as long as you can stand it.

Hey Jim,
I thought I would try and help translate "as long as you can stand it".

White pines in general are not as vigorous growers as JBP, this recommendation is for JWP, not JBP.

Wait, you should allow a second growing season after the grafts showed signs of taking. So if you did the grafts in 2013, and in 2014 they finally began to grow, you might be able to cut off the original foliage after the 2015 growing season, so late winter or early spring 2016 might be time to remove old foliage.

You need to look closely at the grafts, make sure the fusion is fairly complete before removing the original. You need foliage to draw sap up to keep the trunk alive. If the grafts are too small to draw much sap, when the original is removed, parts of the cambium of the trunk will die if there is insufficient sap flow to keep it going.

One tactic is to reduce the volume of the original foliage for a growing season, then the following season remove all of the original. In the above scenario, in late winter-early spring 2016 reduce the original foliage by about 75%, then in late winter-early spring 2017 complete the removal.

If your scions grew rapidly, and have a volume of foliage that is as large as 25% or more of the original, you can speed up the process, but a little tuft of a scion growth will not be enough to keep a large trunk of a tree alive.

With more vigorous pines like JBP on say a ponderosa, the principles are the same, but because JBP tends to be a fairly vigorous grower, the whole schedule can be compressed, sometimes to just 2 growing seasons.

I would be very patient before you cut the original foliage totally, I would wait at least three years. Reducing the foliage a small part at a time. The JWP I grafted on a JBP still had only one tuft of BP foliage and was growing well, but when I cut the last of the BP foliage the graft failed.
Whether it was cut at the wrong time or too early I don't know.
So I would also say: As long as you can stand it, let the scion get strong and gradually take over the under stock before you cut the final foliage away.

Great, thanks for all the advice, I hope in a few years to be able to post some pics of it when I begin to think of styling it!