Confused O day?

Kay • Mummy to precious angels too beautiful for earth👼🏼💕
So I have now 5 apps on my phone to track my o and af days. Kindara says I Od 27th, fertility friend says 28th, glow and ovia says 29th and my days says 30th. That makes me 2-5 dpo which will make testing so hard..
​Anyway according to these apps I am due to start my period anything from 11th-15th October. When would you ladies test?