I am obsessed with my sons naps and sleep. I just feel so strongly about him getting good naps and night rest. For him and for me! I need that time to myself to feel sane.

Just want to preface by saying that I have been holding on to two naps for dear life. I knew around now he may be ready to drop - he's 15 months next week.
It's been about a month now of the "some days he needs two, some days he needs 1". We'd have a few days where he'd take his morning and afternoon naps no problem, 1.5-2 hours each. Then we'd have a day or two where he'd refuse one of the naps (usually afternoon) making for a very long day for everyone.
We're now on day 5 of refusing afternoon nap. This is the longest stretch of consecutive refusals. Does this mean it's inevitable, time to start moving the morning nap to one afternoon nap, little by little? Could there be some other reason he's refusing? Should I just try to space out the morning and afternoon by more? (We do 3 hours between naps). I just want to be certain he's ready and it's now undeniable. Interested in what other sleep-obsessed mamas think.

Also, how did you do it? I've read you slowly move the morning to afternoon and for a few days/weeks bedtime may have to be really early to compensate for the longer afternoon. Is this what you did? How did it work? I do lots of research but always curious how it worked out for real life people