Full disclosure; I am not a manager of anyone nor do I work in a software company. However, I work in an industry where things need to be timed out pretty well and I have to constantly provide an answer to my bosses and colleagues of the question "When do you expect to be able to do X?".

From my perspective it involves two things.

First, it is about applying the experience of similar situations to the future. I can't very well tell my coworkers "I don't know" because the work that they do depends on me getting my stuff done, especially in a timely manner. Thus, I have to draw on previous experience to say, "Well, this (or something like this) took me two weeks to get done last time so it will likely take me a similar amount of time this go round."

The second part of that is being open with expectations. Being up front with my coworkers involves me telling them that while I think this will take X amount of time, these are the complications I am facing that could have an impact on my ability to deliver in the provided time frame.

Ultimately, by applying a combination of those two things I have been able to build a good relationship with those I work with when it comes to providing estimates and expectations for delivery. Honestly, not sure how this will apply to software engineering or if it is even translatable at all, but that's my two cents.