when to get rid of a Blackbird nest in my house?

I have a blackbird nesting in the toilet exit pipe in an upstairs bathroom in an extension I am building.

We are finished plastering externally, and nearly finished internally. The blackbird female is there all day every day, and I don't want to mess up her plans for her nest but I need to remove it as soon as its safe to do it. Worst case scenario is that my plumber will need to plumb in and test the toilet so the sooner the better.

Any advice how long I need to wait?

thanks!

Steve