By making an appointment to apply for "titre de séjour", you will showing your intention to comply with the requirement.
Unfortunately it is now common place in many places not to be able to get an appointment within the required timeframe and these institutions are very aware of that.
Most online appointment systems require you to give the reason for the ...
Are you sure you need to apply for ‘titre de sejour’? I might be wrong but in most long stay visas you need to validate your visa online and the process follows.
This is what I did for my appointments. I received the medical appointment in a week of arrival but still waiting for OFII summon.
Your process might differ but worth checking.