1 month of your own concentrated work? 2 quarters easily, because at this scale:

- You’ll get a bunch stakeholders each requesting a different format of progress reporting.

- You’ll get pulled into dealing with a small but disruptive emergency that requires unique expertise.

- A dependency will change in a way incompatible with your work in progress.

- You’ll hand off the half done project to the new hire.

- You’ll need to rediscover what the project is about after the new hire hands it back.

Not that I've used this extensively, but months would likely increase to quarters.

And if you're estimating something to the lengths of months, you're already into project management territory size, rather than broken down to development/delivery sizes... The amount of unknown unknowns and other uncertainty certainly warrant happily estimating years length, surely.

Also #NoEstimates (=