I had a 3 day transfer also. I did my first hpt 14 days after transfer and it was positive. I then got a positive beta with a 1200 hcg level on day 16 after transfer. Since I had twins that was probably why my beta was so high and probably why the hpt picked up a positive instantly too.
Of course many people get negative hpt's and then get a positive beta.
ME 36, DH 49
TTC 10 years
5 Failed IUI's
1st IVF Feb 2006 - TWIN BOYS Tyler & Brady born 9/30/06
I got BFP on both 2nd beta (blood test w/ doctor) & on HPT 10 days post 3 day ET on my prior IVF cycle. In my 2 ww this cycle....get my 2nd beta on 8/21....