That show better be a long ways off if your buying the tricks now. The rule before adding anything to the show is 1 hour of practice for every minute the trick takes (include timer for patter) then 1 hour of rehearsal for every minute. Yes there is a difference. Then if your trial audience approves you put it in the act.
HaHa! That is actually good advice for the average trick. I may adopt it myself. I'm chuckling because of some of the card effects I have been working on over the last few months. Try 10 hours of practice for every 1 minute of performance! As long as you are selecting easy effects I think that is a good rule of thumb. So if you want to do a twenty minute show of fairly easy effects then you should be ready in a month or two of moderate preparation and you might succeed in two weeks if you really dedicate yourself for those two weeks. The problem is if you accidentally select a difficult trick it could derail your whole time table. If you are new I would stick to mostly gimmicked effects. Sleight of hand is a lifetime dedication.
Look up candy factory. Always a nice encore trick for kids.