I consider the deadlines and who is involved in accomplishing the task. For example, if it's all on me, I can easily determine what it might take. When it involves input from others, I consider that I might not be their singular priority and allow extra time to hear from them. Honestly, I ratchet up the timeline in case they manage their time based on my deadline, which may be missed. So i establish a deadline for their input that will help me deliver within expectations.