How many days after a faint line can u use a digital?

How many days after a faint line did you receive a positive on a digital?
 I don't want to waste money trying too early. I have NO idea when I ovulated- I'm 4 months post partum,  breastfeeding, but did have a period a little over 4 weeks ago. I've been pulling faint positives for the past 2 days. 
Side note- I've taken a million tests. 🙈 LOL! It's hard to see the VVFL in all of them, but it's there in person, promise. Not really trying to debate that, just want to know how long until most ppl receive a positive digital after a faint line. I don't know how many days past ovulation I am.