Unfortunately I’ve seen too many people share the myth that you must exchange your licence within 6 months. Not one licence is required to do this.
It is 18 months if you hold an EU passport, excl French, but that is only if you hold a non-EU licence, you have to be in France for 6 months and then you have 12 months to submit an exchange, so 18.
There are a few different scenarios, but ultimately your licence determines the exchange procedure, but your nationality determines when you have to exchange and what documents are required.
that is, license related?