DS is 2.5 and we do 1,2,3 timeouts with him. Unless its hitting, biting, bad words etc, then it is automatic time out without warning. When we started this he spent a decent amount in time out, now it isnt even a daily thing. I usually get to 2 and he is back on the right course. Sometimes I know he is just acting out, out of boredom or needing attention and I try to catch that and point him in the right direction, give ideas, or entertain him to avoid naughty things happening. if he is acting out bc of tiredness we just do an early nap and that helps 100%. I've noticed since starting time outs I've learned to read his acting out cues/what he needs much better and it has helped us both tremendously. He just has a ton of energy,and I do not.
Can I ask how long it took for your DS to get it? It's working reasonably well with my DS (same age) but once he get's a 1, it's no-turning-back for him, and he inevitably gets to 3 right away. I'm still waiting for him to understand that a 1 doesn't necessarily mean he has to have a time out.