A range just slides in, so you can definitely finish everything else and start using the kitchen while you wait. I would also see if the dealer has a loaner range that you can install and use while you wait, even if it is a smaller model. Or keep your old range to use while you wait.

Many of us here built complete houses during covid. You just adjust you expectations and improvise if possible.

A word of caution about executing a remodel and leaving a space for an appliance to be installed later: That strategy works fine where manufacturers are producing appliances to standard dimensions and substitutions are easy to make. In the case of a high-end European range, if the model you order is discontinued between the time you place the order and the expected delivery date or something requires you to make an alternative selection, you'll be constrained by the original range dimensions. Your choices will be limited accordingly. In the worst-case scenario you may be required to modify cabinetry that's installed.

@Charles Ross Homes, Lacanche has been around for 200+ years, and 30+ under its current line-up. the 55" Sully is one of the most popular models in the US and Canada, I don't foresee it being discontinued anytime soon :)

Leaving a void in cabinetry to be filled with a component that's not standard dimensions and takes over a year to get is a calculated risk (reminds me of a certain mail order bride story, but I digress.) It's up to the OP to assess that risk and their willingness to deal with a potential change if necessary. Leaving a 55" void leaves less options for filling it than a 30" or 36" or 48" or 60" void. Bonne chance!