Amazon AWS shipment pickup times

I am going to be using AWS shipment pickup via LTL for the first time as opposed to sending smaller amounts of product. For those that have used this before, how accurate are the pickup windows for 3rd party carriers ie: (freight ready by dates?) I am running a home based business so having some difficulty with the logistics of getting a pallets of goods onto a truck and headed to them without it sitting outside for any extended period of time