Planning software projects — especially estimating timelines — is a consistent challenge for developers.

When I ran an agency, I constantly struggled with my team's ability to hit deadlines until I figured out how to plan more effectively.

I've written up my approach here:
http://lengstorf.com/effective-project-planning/

The short version is:

1. Make every task a yes/no question. If there's room for interpretation, it's not clear enough.

2. Keep the goals visible and track progress in a central location (somewhere you can both see).

3. Break tasks into single-day efforts whenever possible. So instead of "build home page", it's "A) style navigation; B) create opt-in; C) add testimonials section; etc." — the goal is to create momentum with a daily deadline that can absolutely be completed.

It takes a little more effort up front, but it pays dividends in the long run. I used this strategy with my team to decrease our average turnaround times by nearly half, and my consulting clients have used this strategy to similar effect.

I'd be happy to help you create a concrete plan using these techniques. Schedule a call or send me a message and we'll get started.

Good luck!