Yep, this exactly. Your estimates will get better as you have more information, so keep everyone updated as you get into the thick of it. This is why Agile has

Yep, this exactly. Your estimates will get better as you have more information, so keep everyone updated as you get into the thick of it. This is why Agile has daily standups. If you don't have a daily status call, do try to get into some sort of routine update. It also helps if you know what is the highest priority and what can get sacrificed. If you're late, talk about it in your retrospective. Taking time to look back will help you make better estimates in the future. Often times I gauge how reliable an engineer's estimate is based off of how many questions he/she asked me during the kick off meeting.