i was just wondering if there is any particular time in a monsters life where it will work best to give a monster a gold peach? I mean should i not give it a gold peach if holly already gave me the old age warning? just wondering....

It may be too late then. I don't recalle xactly about MR1, but I know that in MR2, once you hear that warning, peaches don't act properly -they only set the clock back a couple months.

I like to feed them a year after prime started, that way they go back to the beginning of prime, when the statgains are best, and re-live the best year of their life.