Safe on time deliveries to our stores and clubs is job one and its taken very seriously. Having a store late is a huge deal here and you will need an explanation (dc late,accident,traffic),being late because you like to screw the pooch will not be tolerated. There have only been a few times that I have felt under pressure in the year I have been here most of the time I just move along. I have had two lates both were due to road closures resulting from accidents. 90% of the time you can move at your own pace and as long as your getting the job done no one will question you. You set your times and they work off your numbers so if you need to pad a little for traffic then do it.
A large portion of the work load is done on a "pull ahead" system,meaning trailers are delivered to the stores the night before. The transit times set for same day trailers usually give a one to two hour cushion.
Vendors are different and its usually you get there a soon as you can. The majority of our vendors are drop and hook and a large number are 24/7 which makes it easy on our drivers. Live loads will usually have appointment times but they are for the most part treated as "soft" arrivals,meaning sometime during that business day. Missing a pick up is no big deal if you have one of the valid reasons I mentioned above. Its fairly common for us to be over booked and rescheduling appointments happens every day. Once again you are expected to be a professional that has experience managing their time. Keeping the office informed of delays and possible missed pick ups as far ahead as possible is part of the job.