Son got his second monthly sustenna injection. Talking too much and too loud

My son started his second month on invega sustenna injection. I can not say for sure if I see any improvement. Before starting sustenna he already been on risperdal consta for 8 months and before consta he had been taking risperdal m-tab for 6 months. While switching him from consta to sustenna doctor expressed that he was probably on a very low dose (37.5mg) of consta. So my son got his monthly dose of 156mg of sustenna. I have been suggested by some of his previous care takers that as he has already been on risperdal (base compound of risperdal, consta and sustenna ) for almost 14-15 months, I should not wait for too long for invega to show results. If invega does not start showing improvement in a few weeks may be 6-8 weeks, then we should start considering other options. May be risperdal is not the med for him. Remember the basic salt in all three (risperdal, consta injection and sustenna injection) is the same. At the same time I am really praying that invega sustenna (being a monthly injection) works for my son. But I am wondering that may be I am not noticing some subtle signs of improvement or may be there is no noticable improvement at this time.

give it the full 6-8 weeks, when they put me on Geodon it took a two months before the meds took full effect