How Instagram orders a following list.
Updated
On your own account
Open your profile, tap Following, and there is a sort control offering date order, oldest or newest first. It also groups accounts Instagram considers least interacted with.
This exists because it is your data and the purpose is account housekeeping: finding people you followed years ago and forgot about.
On someone else's account
There is no sort control. The order you see is produced by Instagram's ranking, and the strongest input is the relationship between you and the accounts on that list. Accounts you also follow, and accounts you interact with, tend to surface first.
Two consequences follow from that. The same person's following list can look different to two viewers. And the order tells you nothing reliable about when they followed anyone.
Why people think the top of the list is the newest follow
It is a reasonable guess that used to be closer to true, and it still occasionally lines up by coincidence. But it is not a rule, and acting on it produces wrong conclusions.
If you have ever seen advice along the lines of "the first account in their following list is who they followed last", that advice is wrong.
How to actually see recent follows
Since the list order carries no timestamp, the only way to know what changed is to compare the list against an earlier copy of itself.
Record the public following list now, read it again later, and the difference is the answer: every account added and every account dropped in between. That is exactly what our recent follows tool does, on a weekly cycle, with each new account analysed so a new follow into a gambling or diet community reads as that and not just as a name.
Related questions
Can I sort someone else's following list by date?
No. The date sort exists only on your own account. On another profile the order is Instagram's ranking.
Is the first account in a following list the most recent follow?
No. The order is ranked by relevance to the viewer, not by date, so the top name is frequently an old follow.
Why does the same following list look different to different people?
Because the ranking takes the viewer into account. Accounts you also follow tend to appear higher for you than for someone else.
Does Instagram show the date someone followed an account?
Not for other people's accounts. That timestamp is not exposed publicly anywhere in the app.