When you vape THC, you usually feel the effects pretty fast sometimes in just a couple of minutes, and almost always within ten. The high hits its peak about 20 to 45 minutes after you take a puff. Most people stay high for one to three hours, though this depends on things like your tolerance, how fast your body processes THC, and how strong the vape is.
References
[1] How Long Does a THC Vape Effect Last? Understanding Cannabis High Duration
