You'll feel a lot of things.
HRT, whether it be placebo or real effects will quieten the dysphoria to varying degrees and other stuff will begin to manifest.
In my case I'm on full, steady, officially monitored HRT for a month now. The dysphoria is pretty much gone now, but I feel guilt about what my transition is doing to others. Especially when I'm confronted by my wife about it, even if her accusations are unreasonable and unfounded (in my opinion).
I guess that's what happens when you take dysphoria away.
Well, I shouldn't say that it is totally gone. Last night's new years eve on TV was unwatchable for me. Everyone was out and about being themselves and I'm still not full time... to fix that, 2015 will be the year that I go full time. I was planning to do it in the summer but I may bump it up a bit. Beard shadow and voice are the major things holding me back now and once I get those managed I'll have confidence to move forward.
So hang in there, it will happen for you as well.