AKA “Help! I estimated a project and hit every branch falling down the surprises tree.” A shocking turn of events that definitely has never happened to any of us.

Don’t worry too hard when it turns out estimates weren’t accurate. They were optimistic guesses based on incomplete information and optimism that everything would go right—which it rarely does.

Do communicate to your stakeholders. Tell people whose work depends on your project about delays as soon as you know. Communicate now instead of waiting for the next scheduled update.

Don’t let your team think they have failed. If they executed well but surprises came up, tell them so explicitly. If they aren’t executing well, address that separately.

Do re-evaluate your plan with fresh estimates. If the deadline is fixed, cut scope. You can’t count on catching up by working smarter or having better luck.

Don’t ask people to work harder or longer to catch up. There’s no catching up, only keeping pace, reducing scope, or slipping the deadline.