if you want to make ur tama get to adult faster...the only thing i can think of is to debug it...but you have to be very careful about it...i debugged mine..but I did it too much to the point where it was going hyper speed and was born then grown up then dead in a minute or less.
about the destiny star...fourth gold really is not too hard to get. Do you join the competitions? try to be in the top 100 (but aim higher for top 10 or 11-30) your CD level will raise in no time. Ex: I just entered a competition with 6th super silver...after one competition my CD raised to 5th ultimate. After 1 or 2 more contests with good results I will be up to 4th gold. It takes a little while but its the easiest way...playing games to get it up that high will take you FOREVER!!!
where is your CD level right now?