PLEASE READ!!! Kinda long, kinda venting, but a serious question towards the end 😁

I started using OPKs last cycle, and I bought them close to my predicted fertile window, so I started using them the day I bought them. I got my positive LH surge on the third test. 
I'm a mess this cycle, just a lot going on as far as grad school, work and trying to keep up with laundry/dishes (home stuff in general). My period has been SO off... At first I was two days late (totally abnormal) and now up until last night/random today I am still withdrawal spotting...you know when you have sex and you thought you were off your period and then he pulls out and BAM that bitch is there again for a few hours or even another day?? Well that's been my life. I'm on CD 8, still brown spotting randomly today, and usually I'm done with my period by CD4, 5 at the absolute latest. I know stress is a factor. My boobs are killing me all the sudden and I have these scary ass blue veins all over them all the sudden. 
I know this is long and I'm giving a life story, but it's nice to vent for a second. But real talk here is my question lol:
When do I start testing for O? Do I wait until the spotting is completely absent? Or what? I don't want to waste tests bc I have the FRER ones that are sorta pricey. 
I REALLY wanna be accurate at testing this cycle, bc I have my first fertility appointment on the 18th. So I want to go in to my doctor prepared.