I prefer to not give exact estimates whenever possible as the unknowns will ruin your estimate anyway.
If necessary I prefer to get very clear what is needed to [make that sale/give that demo/whatever they need] and give a very conservative range with a bunch of caveats. The more flexible the requirements and timeline the better. It means with a bit of luck you can deliver early and/or throw in some bonus stuff at the end.
If you are inevitably going to miss a deadline, discuss it as early as possible and discuss how to proceed, where to focus etc. You can often reduce the scope, cut more corners, move the deadline, find more resources, or do damage control. Whatever is necessary.
That's why I don't think (accurate) estimates matter too much, it's more about communication, managing expectations, and being flexible enough to adapt along the way.
If necessary I prefer to get very clear what is needed to [make that sale/give that demo/whatever they need] and give a very conservative range with a bunch of caveats. The more flexible the requirements and timeline the better. It means with a bit of luck you can deliver early and/or throw in some bonus stuff at the end.
If you are inevitably going to miss a deadline, discuss it as early as possible and discuss how to proceed, where to focus etc. You can often reduce the scope, cut more corners, move the deadline, find more resources, or do damage control. Whatever is necessary.
That's why I don't think (accurate) estimates matter too much, it's more about communication, managing expectations, and being flexible enough to adapt along the way.