Advise on when to test

So I started spotting on Jan17th spotted for 5 days bled for 2 ending on Jan 23rd.  I took clomid days 5-9.  Started taking OPK on day 10 and finally got a surge on cd17 and a positive OPK on cd18, 19, & 20.  So here is my question maybe I shouldnt have started counting my cycle on my 2nd day of spotting like my ob said to and I should have waiting for full blown blood to begin counting?  So here I am 4dpo and wondering do I test on cd28 or wait till 10dpo?  Man I hope thats not to confusing!
Thanks for any help you can give me

PS Anyone have implantation cramping? 
Just seems I have been gassy feeling with lil twinches...I dunno

im not sure.. i always waiting until after i actually missed my period... i hope someone has better answers for you... good luck