Ill give u some spawn times
Blue/red buff = 5 minutes, usualy comes back around 7.10 if u start at blue, so watch your times, you dont want it to get stolen.) you can also ward their buffs to try and steal theirs. or setup a gank if u know the timers.
Dragon = 6 minutes.
Baron = 7 minutes,
little creept (not sure, think it was 1.30 minutes)
The thing with the original buff might be that u killed the enemy jungler, if u kill him, you will get his buffs and the timer will just reset. so you will have another full buff duration.