I have been stacking SMASH with SizeON for the past little while.
The SMASH covers your preworkout creatine (30 min before)which is predominantly CEE, and then the SizeON is taken during/post workout and say you workout in the morning you take the other dose of SizeON in the evening, and vice versa.
Thats my recommendation. GL with w/e you do tho man.