Nothing is more frustrating than having orders in house that can't be shipped due to a parts shortage. Keep a record of delivery times for all parts. Ask your sales reps to give you best guesses as to expected volumes. For a new product, these truly are guesses, but until you establish some history, they are better than nothing. If you do have a situation where deliveries will be delayed, call your customer and explain the situation.
People appreciate honesty and understand that delays can occur.
Just don't make a habit out of late deliveries. Remember, your reputation is being formed daily. Bust your butt to deliver in a timely fashion. As a young company, you will be pleased when you find a supplier who is willing to work with you, give you what you need at a fair price, and maybe even give you net-30. When you find these folks, treat them fairly by paying your bills on time and giving them your repeat business.