Sorry if this is a dumb question. Ok so I bought 1 ml of distillate and some Terpene Liquidizer. I feel like if I mix the whole 1ml with 1ml of terpes and then fill my vape cartridge, eventually it will go off as I won’t be able to vape it all in a short period of time. On the other hand if I mix a smaller amount, it won’t be enough to soak into my vape cartridge. Should I just mix it and then put a couple of drops of the mixture into e-liquid and vape that way?

Providing the thc and ejuice are warm enough to mix together, yes. But it would seem impractical to do it that way, to me anyway. I'd rather mix it all together, over adding a bit at a time.