There is also a BBT adjuster you can use if your wake up times are inconsistent. I used that for this baby as DS would wake anywhere between 4.30am & 6.30am. So I set my "usual time" for 5.30am and took my temp when I woke (whenever it was) then adjusted it. It worked really well. Just google BBT adjuster - there are heaps online. I was also using OPKs which I got from lullaby conceptions. I can't remember how much they were but definately less then $25 for 7 days.