Four of us are travelling PER-SIN-CDG in mid March. I understand that you can select your seat on-line beforehand. How early can this be done?
Welcome to AFF, Mr B.
For Y bookings:
If you purchased on singaporeair.com(.au), you can select your seats immediately, and change them anytime online.
If you purchased from a travel agent, no advance seat selection is available (except to specify aisle or window thru the call centre.)
For J or F bookings:
If you purchased on website, you can select immediately etc.
If you purchased from a TA, your TA can request seats, or you can call SQ direct to select.
If your bookings are award redemptions, seats are selectable at time of redemption, if made on line.
If made off line, only J or F seats can be preselected, thru the Call centre.
In all cases, you can do on-line check in from 48 hours before departure, and select your seats there.