OK, just to address the loss of momentum scenario you mentioned, I thought I'd throw in my own example.

Today I arranged a date with girl I'd met 2 months ago. The last text she sent me was 4th Jan. I then sent one 10th Jan with no response. Thus this all seemed like it had died. Then last night:

Me: Hello ***. How were your exams... I hear the exam season has finished
Her: Yep, I finished, just wanna tell you
Me: Well, I just wanna tell you... I'm free for tea on Thurs or Fri... which is better?
Her: You mean the afternoon?
Me: How about 4pm
Her: Yep, I think I'm free Fri
Me: Cool let's meet at ****
Her: OK, looking forward to it

The main point being that there was no momentum. I was straight to the point. No need for long drawn out text conversations building up to asking her out. I had spoken to her over the phone once a couple of months back, and had a flirty little text exchange before Christmas, but that was it.

I kind of thought this was dead in the water, but thought I'd give her a go and fired the text just to see. Now I have a date.