Dragonflight on PTR

Hello since i can't find this anywhere and i know it's still a bit too early,but,this is my 1st time waiting for new expansion while i play current one,does anyone have any time frame idea or if even Dragonflight will be on PTR?

I don't think i'll be lucky enough to get into Alpha or Beta but PTR is accessible by almost anyone so did they put previous expansions on PTR before release and how close to launch was it?