John Doe wrote:
wrote:

At what point do they adjust their orbit during launch ?

Do they fly straight east from 28.5 and "turn" once they reach the
descending node at equator ?

Or do they fly south east on launch until they reach equator and then
turn where they accelerate into proper due east ?

Or do they actually reach 28.5 LEO, and only while boosting to geosync
altitude do they adjust the orbit to become equatorial ?

Not while boosting, after you get there (or higher even). To do a plane
change while keeping the same speed, the velocity change is
approximately:

dV = 2V * sin(theta / 2)

Where V is the initial (and final) orbital speed and theta is the
angular difference between the planes. So doing the change when the
velocity is at a minimum (at the highest altitude) is important.

Combining it with another burn (such as a circularizing burn at apogee)
would use less fuel than both independently, though.

--
Darren