I don't grow seedings so I don't have experience with this. As I told you before, Weldon Delp was the self proclaimed champ in getting seedlings and cuttings to bloom quickly. Commercial nurseries actually let the buds open into new shoots and then root the pinched shoot, but it will delay the time to bloom. Actually the rooted pinched shoot may bloom faster than the original seedling will after it has been pinched.

One technique that Delp did with deciduous azaleas is:
"If you are rooting deciduous azaleas and are having difficulty getting the axillary buds to break dormancy then try the following; Four or five days before you want to stick your cuttings , pinch the tender tips from the cuttings. Leave cuttings intact on the plant. In four or five days remove the cuttings from the plant and stick in your rooting bed."

Delp's trick for getting rooted cuttings to branch more quickly was to let a tip bud open and start growing a new stem. Then remove the tip of this stem but leave the juvenile wood. He claimed it had auxins that provided apical dominance and these auxins would relocate down into lateral buds making them open several months earlier. Maybe some people call this a Delp pinch.

Harold Greer is talking about pinching the new shoot bud just as it opens and before the juvenile wood forms. This is the more traditional approach.

Here is a link that might be useful: Delps accelerated propagation