When to start OPKs?

B

Hello! This is my first month (cycle 9 or 10 of TTC) trying OPKs, but I’m not exactly sure when to start testing. My period ended Monday, but I’m a bit irregular. For instance, this past period I had almost a week of spotting before having my actual flow start, some months I’m 35 days, but then occasionally I’ll have a 50+ day cycle. Should I just start in a week or should I start right away and see what I get? Thanks for the help!