I started a few months ago I believe (too lazy to check my own profile to be sure) but probably a bit more than a few months. But that's only PokeCommunity.
I used to visit Roleplay Guild, and a dozen other sites I forgot the names of, and even joined "The World's Biggest Roleplay Group" on facebook, though I rarely visit the latter.
Someone close (almost like a son, even though I'm only 17) had been RPing on here for some time, I'm not exactly sure how long. I think he preferred going by "Silver Dracul" though he could have used a different name here. Anyways, He's been gone for quite some time, I miss him a bit. My point is, he would always borrow my laptop to get on, and I found the address after he left, but I was adamant on joining. "As much as I like Pokemon, RPing it would seem too childish to me." However, when I actually checked it out, I changed my viewpoint and gave it a try. First PTA, followed by Earth&Sky, and now Power Sprint as well.
So, tl;dr
Time on PokeCommunity: 4-5 months
Roleplay in General: 8 Years (Give or take some months)
Yeah. Been playing these for quite some time now. Though I've never been in a finished RP.