use those aged and warmed up accounts (more expensive) that you're able to login to create the thread you want,
then used a few churn and burn accounts that are able to post to post in the thread,
use the 1st account to enable those "churn and burn" accounts to be able to post on your thread,
and keep changing accounts to promote your thread.
that's all i know,
after you buy a few rounds of these account consult with the "reddit account seller" on your intentions and ask for help there.
hope this small tips helps.