Counting how many days it takes to complete a project that has no deadline

We have projects that we want to be able to track how many days it takes to complete while we don’t have the deadline.
Is there some sort of formula we can create to either have the time tracking convert to days or just have a formula column where we have a start day but no end date?
Example- We have a house we put as an active property on 2/6/2020 and want to see how how many day on market before it changes status.

Hey, I think we’d need more info to help but I think you are saying…

If you work 1 hour on a given day and 8 hours the next, it doesn’t matter, that’s 2 days. Right?

If that is the case, have an “hours” column for your time tracking then another Formula column that uses the following function to convert anything less than 8 hours of time (you could say 12 too) to a 1, meaning 1 day…

ROUNDUP({the name of your hours column}/8,0)

Hope this helps.