ovulation strips..

Leyann • TTC no1: 06/15🤰fell 31/12/16 -> Daughter 08/09/17👶🏻TTC no2: 12/19🤰fell 04/02/21 - lost 31/4/21 👼 fell 13/08/21🙏
So finally after a year I have decided I shall test with ovulation strips. Not a clue how it will help? 
Any tips for me when to start them?
Ps periods are slightly irregular..