I understand you perfectly!
I also thought if it was so easy because no one had done it. Honestly the routine works perfectly and does what it should do, I even looped to load 50 continuous images and did not give any problems as does the Vs. Bar Personalizable of Invert that after loading 5 images hangs the game. But yes, at the hardware level it should be loaded into the buffer and loaded into the VRAM with the next vertical sweep. I will continue to research and try to improve the routine.
With respect to calling a msgbox after the image, it simply deletes the image completely and loads the same text if I call a showpokepic. But if I call the showpokepic before the image both are kept on screen without any problem, something that can not be done with the routine I mentioned before.
Thankful with your advice and any changes or improvements you can make to the routine to do what is promised without problems, will be welcome.