I worked with a lady that had been flipping homes for a while that got into a groove with her teams and material suppliers that told me her way of going about it. Not saying this will apply right away since you're new and everyone is going to have a different way of going about it but I found it interesting and wanted to share.
We were looking at a house that she wanted to flip and I asked her, "The property needs a good amount of work. How long do you think it'll take to fix up and put on the market to sell?"
She replied, "The way I estimate my project time is by allocating $10k per week. For every $10k I spend on the rehab, barring any acts of God I should have that portion of the work done within a week. If I have my materials on site and on time my guys know it needs to get done." ($30k rehab budget = 3 weeks project time)
Again, I'm not saying this is going to fit everyone. She's very experienced and has all her ducks in a row. There are a ton of variables that come into play during a rehab, a lot of moving parts to keep track of, and a detailed schedule to stick to is a must. This was her method of estimating time and with as many projects as she's taken on, I didn't feel like arguing/questioning her logic.
In this business, the quicker the project the better since time is money. That doesn't mean projects should be rushed by any means. Quality work will go a long way.
To give an example, an investor I know just bought a house that needed a layout restructure (basically redoing the layout of the house to make it more functional and attractive), installing central HVAC, building out a washer/dryer room, plumbing (new bathroom and kitchen location | rough in + top out), full electrical rewire (after full demo to studs), new sheetrock, paint, flooring, kitchen/bath finish out, and exterior restoration. Him and his GC estimate they are going to get the project done in about 4-5 weeks.
I hope this helps and any other feedback is appreciated!
Cheers!