If you keep a dedicated too head for each calibur, which I do and highly recommend, calibur changes are fast and easy. There are 4 parts at most you would change, the tool head, shell plate, primer parts, and case slider, but they only take a minute or two each to do, and if you are loading the same primers size, or similar case size, you wont need to do all at once. When I switch between 9 and 40, its a simple tool head and case slider swap, can be done in a couple minutes.
I usually do a cleaning job between caliber changes which doesn't take very long either, maybe 15 mins depending on how dirty it is and how in detail I want to be.
Are you ordering from a Lee dealer or a kit from Amazon or somewhere like that? If a Lee dealer, I would suggest getting a few other odds and ends while you are at it to save on shipping.