Are the effects of smoked marijuana felt within minutes and may last for 2-3 hours?

Yes. These effects (when smoked or vaporized) are felt quickly and last typically around 2 hours. When consumed orally the effects are not felt quickly but also last for a few hours.

To further add, first time users may not feel the same effects, and may not feel them as quickly.

Typically it’s lasts 3 hours, but it takes 10-20 minutes to take effect