I did two water-reservoir-modified approach grafts (I put the name together myself, but it makes sense), they were long green, freshly-cut scions with water bottles wrapped in cellophane with the scions so that I wouldn’t have to refill the water bottles and risk breaking the callous, and the water bottle were tightly taped to the tree below the graft.
I did approach grafts on the trunk and on a branch and after about a month one was working and the other had no growth, so I pruned off that whole branch, when taking the water bottle off of my scion, I saw it had fully calloused over and the buds were just starting to swell, it probably wasn’t the longest I waited for a graft, but I think it was a whole month from the end of July to August.
From a video I did, I don’t have a picture unfortunately
The growing graft, after cutting off the lower end of the scion going into the water bottle.
The callous in a close up.