Monday Hour One. Unpredictable work schedule.

My husband and I run a new business together and we sat down and did our first Monday Hour One together this past Monday. The business we have can be unpredictable. An example is we get a truck order almost every week and we do not know when it will arrive until a day prior. The day the truck comes in the driver calls about an hour before he will be at the shop and we have to drop what we are doing and go meet him. We also set up same-day appointments with customers. We are not at the shop unless we are meeting with customers. Somedays we have no appointments and somedays we have 5. We usually set up appointments the prior evening for the following morning or in the morning for the afternoon on the same day. We do not have to do appointments together all the time so some things on the calendar can be done by one of us and the other can go to the shop to meet customers. With Monday Hour One I know you are supposed to stick to your calendar but are there exceptions? If we have a focus time scheduled on Wednesday but get a call that the truck order is coming on Wednesday should we just move the Focus time to Thursday since we have to go meet the delivery driver? Also, with our business model, we do not rush out to meet customers. If they call and say can you come to the shop right now we do not rush out and meet them. We give them an appointment that is at least a couple of hours later from the time they call. This helps us control our schedule and it works great. I could it be overcomplicating things, but any suggestions would be greatly appreciated! Thanks in advance!