Visa appointment date may be up to six months before the visa start date
TLS has a general FAQ page for visa applicants including Schengen Visas which may be of interest.
The content about biometrics and fingerprinting is useful because this subject is not discussed on this website
The other content has not been cross-checked against what is stated on the 180daysinfrance website
The link is here: https://visas-fr.tlscontact.com/faq/gb/gbLON2fr#tls-faq-1314