I have built software for a number of startups in the last 8 years. One thing that has been constant is how difficult it is to come up with time estimate for how long a feature will take to build.
painful truism from @garyvee pic.twitter.com/3ViMSmeJ3cCasey Neistat (@CaseyNeistat) November 12, 2017
Its important to estimate though, even after being wrong all this time. You need a milestone date for when you aim to complete a feature and each time you go through this exercise you get better.