The top 10-20 follows on Keffals profile never change, however under that block of people the new people Keffals follows is in chronological order, with newest at the top.
This is partly how finding Keffals (Now ex) gf's Twitter account was so easy.

A follow acknowledgement by this account is the most recent Like on Keffals profile, posted on Feb 19th. and is just slightly below these 2 blocks of follows:


It's been awhile and I lost track of exactly where the line between "old follows that are left at the top for some reason" and "newest follower" is however I believe that "Mad Molly" is the most recent account that was followed. I'm certain Tempest is an "old follow", so Keffals followed about 8 more people before disappearing on the 21st.
This list has remained unchanged throughout the past month, even on days where Keffals has +3 Following etc etc, so either Twitter decided to change how it's worked for the past 6 months+ or (more likely) the number changes are simply from people either being banned/unbanned/Deactivating/Reactivating their Twitter accounts.