One thing to do is to show your estimates as distribution curves instead of averages. It can be helpful to choose estimates from a Fibonacci scale. Set the pessimistic estimate high enough that it’ll rarely be missed.
Edit: I change the units based on how far out I’m estimating. If I’m estimating the next six weeks, I’ll use hours. If I’m estimating a roadmap I’ll use weeks. The numbers get large quickly (1 2 3 5 8 13 21 34 55 89 144). It’s rare you’ll find yourself planning farther than 2 years out (104 weeks).
As you work, keep updating the estimated time remaining. If the initial estimate for a task is an 8 (between 5 and 13), keep reporting 8 until your estimate falls below 8, then report 5 (between 3 and 8). Avoid reporting intermediate values like 7.
Edit: I change the units based on how far out I’m estimating. If I’m estimating the next six weeks, I’ll use hours. If I’m estimating a roadmap I’ll use weeks. The numbers get large quickly (1 2 3 5 8 13 21 34 55 89 144). It’s rare you’ll find yourself planning farther than 2 years out (104 weeks).
As you work, keep updating the estimated time remaining. If the initial estimate for a task is an 8 (between 5 and 13), keep reporting 8 until your estimate falls below 8, then report 5 (between 3 and 8). Avoid reporting intermediate values like 7.