Georgia was founded with smallholdings in mind and slavery banned in 1732. The ban on slavery was lifted 17 years later in 1749.
The challenge is, from a PoD after Georgia's founding, to have the slavery ban last longer, at least 30 years, 40 years, or possibly more.
Perhaps if the Trustees had been packed with more people of antislavery convictions like Oglethorpe?
I was also going to suggest boosting the Quaker presence, but that doesn't quite help for a couple reasons-
Quakers are not well suited to be the predominant area of what is supposed to be a military frontier province, and opposition to slavery, while increasingly common among Quakers, was certainly not universal in the 18th century.
Is there a period of time after which if slavery is introduced, it will never be tried?
Would delayed legalization of slavery simply mean a lower non-Indian population in general (fewer blacks and whites) and delayed development?
If Georgia is slower developed, is it more likely to stay Loyalist? Or could this domino into slower settlement and statehood of old southwest locales like Mississippi, Alabama and Florida?