It is a fairly normal procedure for new aircraft. No matter which loadcontrol system you work with, new aircraft and new aircraft types are always added too late. If you use codeco, axis, babs or fido, you can add a seatplan to any aircrft you like (probably also gaetan, although I don't know how), but the trim details are only added when the airline submits aircraft data to your dcs (loadcontrol supplier). Under normal circumstances, a dcs supplier takes approx six weeks to add an aircraft.
Until then, you can make a weightsheet, and a manual trim chart.
brgds
FS