Typically about 2- 5 minutes.
I start it up and let it idle, while I'm getting my jacket, helmet, and gloves on.
Then I get on it and sit there for a little while, and when I feel like it's ready, I go.
Generally I'll ride very gently for the first few minutes after I leave the house, maybe 3 minutes or more, before I start riding normally.
I don't give it any really hard throttle until I've been on the road for at least 10-15 minutes.
After that amount of time, I'll give it whatever I want to give it, and it hasn't caused any problems for me yet.
I like the oil to be good and warmed-up, and the whole engine fully heat-expanded before I give her the guns.
The shortest warm up I'll do is about 2 minutes.
But, then I just have to ride gently for that much longer, because I still don't want to give her any hard throttle until she's ready for it.
But, sometimes I will start riding after 2 minutes because it makes me feel like I'm getting out earlier, even if I do have to ride slow for awhile anyway.