I was using some decals today and the temp it gives for using them and I was curious about using them at the same time I fuse the glass since the temp that it recommends firing the decals is in the range that I would fire the pendants that I am making or if it need to be done separately which is how I was taught, although the more I am reading the more I find that the class was a bad one.
Many decal (and decalish products like dichro slide) tend to work better if you fire them on first and then cap them in a second firing. Doing it all at once tends to trap air. You may be able to get away with a single firing on small pieces using a bubble squeeze.