Should I spend all my Timeshards?

First time using the Time Machine, and I already spent just enough to unlock Serve-o, but I'm not sure if I should save my shards for the next prestige to unlock Stab-o, or just spend it all now. If it is better to just spend it now then what Experiments should I spend it on?

First time using the Time Machine, and I already spent just enough to unlock Serve-o, but I'm not sure if I should save my shards for the next prestige to unlock Stab-o, or just spend it all now. If it is better to just spend it now then what Experiments should I spend it on?