19 weeks - movements?

Natalie
I'm 19 weeks today with my 1st baby and for the last week I think I've been feeling movements. Every now and again I'll feel a little thump/tap in my stomach. It almost feels like a large pulse but it's not regular enough to be one...I think? 
Has anyone felt anything similar? 
How long did it take to feel your 1st movements with your 1st pregnancy?