Fuk that go for it. It depends what kind you smoke. There's weed that slows you down, and there's weed that makes you want to run a marathon. Find some marathon. I smoke before (and after, and sometimes during) my workouts, because it puts you in the ZONE. I mean, you can concentrate so hard on your technique, every little movement, you become one with your muscles and you can feel every little fiber and know if your hitting the spot. You can feel the blood pumping in your veins. You become super aware of your breathing and can control your heart beat even when you are doing your 1 rep max's. Seriously, you can really take it to the next level with how much in tune you are with your body movements, techniques, breathing, concentration, motivation, the good things outweigh the bad. That being Said, if you're a dumbass who can't handle his weed anyways, can't stop giggling, can't concentrate, etc, then HELL NO, it's the quickest way to get hurt by dropping a bar on your face, or pulling/tearing something because you're in lala land instead of paying attention to what you're doing, etc etc etc. If you can smoke weed and be focused, you can make some great gains. Especially if you got a (some) homies who also are that way, you can get blazed with them AND GET TO IT RAWR! If you can't, I'd wait until after, for your own safety.