CZHACK, I was in the NAWCC library yesterday and remembered your request for info on Lancelot a Paris. I found Dictionnaire Des Horologers Francais and there is a mention of him. The exact entry is "LANCELOT Francois. Paris. Ch. d'o.1684.".
Mike, In regard to Dictionnaire all I can say is most references listed are short one-liners similar to the one I quoted for you. As for as Ch. d'o, your guess is as good as mine, but I'll suggest that Ch. might have some reference to a district of Paris or perhaps to Switzerland. It's been at least 50 years since I had French in high school.
AFAIK, an apprentice wanting to become a master craftsman had to submit a masterpiece for examination by his guild. If his work was approved, he could set up his own workshop.
Ch. d'o.1684 would be the year when Mr. Lancelot graduated as a master watchmaker.
Apprentices were contracted to the master for, I think, around seven years starting the apprenticeship at around 13-14 years of age.
On completing the contract, they were expected to spend some years as journeymen moving from town to town to gain experience by working in different workshops along the way.
Most never got so far as master craftsmen because beside having the masterpiece approved by the guild, a good sum of money was needed to set up a workshop.
Looking at medieval records, a common thing was for a master craftsman's widow to remarry a journeyman or a young master that could continue to run the old workshop.