The release window for support/lifter toons

With the modest focus of creating support and lifter toons for galactic legends and now special event characters with this current era I am curious as to what qualifications need to be met for support toons to be created and for who. Like how long were every gl out before their respective lifter was released? How long before gl leia and jabba get theirs and why haven't some event toons like thrawn recieved a lifter yet if reworks of old toons seem to have fallen out of favor to be replaced by new support characters for more monetary value? In addition who would be a good lifter for gl leia and jabba?