I've been on HT for 13 months; there was no development for about 3, followed by tenderness and sensitivity. I had some percievable growth by month 4. By month 13, I have reached a small "C" size (sizes?) The nipples have grown somewhat, and are certainly more prominent, The aureolas have grown about the same rate. I guess that's what we mean by "dilation" here, though I've not heard the term used for nipple projection before.
Actually, rather than suction devices, I use the two-fingered adjustment per nipple method.

I absolutely do so not at all because there might be some pleasure attached! It is more than "some". That would be wrong, however I try to be wrong as often as possible.

Two benefits to this method!
Susan Kay