Depending on the complexity of the RFP, you may have between 3 weeks and six months to respond. The time allowed for a response is set by the buyer based on how much time they think it will take you to respond. Proactive companies start work on the first day an RFP comes out or even before and develop a work plan for how they will put their best foot forward. Standard companies leave it to the last week, even the last couple of days. This forces them into generic response mode. Use your time leading up to the deadline well.