How do you estimate the timeline of your own design process?

I would approach this in two ways:

Top down

and

Bottom up

Top Down (Project First) With this approach, the project will set the limits of my estimate - simply because projects, more or less, have launch dates. I will fit my design process on the available timeline. Will take some shortcuts, drop some steps in the process. Will fit the estimate within the threshold of non-compromise.

Bottom Up (Process First) With this one, the design process is prioritized. The project timeline is defined by how long the design process will take.