Sailing from San Juan is no problem; everyone speaks English. It is a US territory.
Flying to/from San Juan on Sundays can be a problem. If you remember that 5 cruise ships full of people( = 10,000 travelers) are trying to do the same things at virtually the same time, you can understand why there can be delays. That said, if you plan accordingly, everything should be fine.
If I ever sailed from San Juan again, I would arrive on Saturday & stay over. Leaving on a 6pm flight was OK; we got to the airport 3 hours early b/c I wanted to be safe not sorry. Flying home on Monday wasn't an option; if I could ever work that out I would.