Hi HJ
Preg symtoms can start as early as the first week after conception. I know a girl who started m/s then and it never went away till she was 26 weeks preg. I know what you mean about not able to wait to do a HPT, as soon as I am 5 days late I do one.
IF your af turns up this month (hope it don't) mark the day in a diary and count 12 days from that day and bd for a few days as these are the best days to do it, and then

Cheers
Chris