There was no electronic communication of any sort (electricity was barely understood at the time), and best case transit time was around 6 weeks each way, often 8-12 if possible at all. It was also highly seasonal, and still very dangerous.

So the absolute fastest turn around time was 12 weeks/3 months, and more realistically 4-6 months. With some decent odds that one of the legs of the trip might sink, losing all hands.

It’s why a literal founding father (and one of the most influential ones) was the ambassador. No one else could be trusted.

[https://www.history.com/articles/benjamin-franklin-france]