What cycle day to start OPK

[Jeb84]

Hi Ladies,

I have decided to try using an OPK this month since my cycles are irregular. My period just ended yesterday. When should I start using the OPK?!

Thanks!

 

[Cppeace]

How long re your cycles on avg? If they average less than 30 days on avg I would start testing around cd 9 or 10. If they are between 30-40 days long I'd start testing around cd 15-17.