Keep in mind instagram's API limits 30/60 actions per hour depending on what bot you are using, reach that limit and you will raise a flag.
Approach it low and slow. If you split the 5,300 unfollowings into 30 days, thats 176 unfollows per day.
Thats just an example but you do whatever you feel comfortable with or whatever your time allows.
Also remember to set your unfollow delay parameters for your bot very high. Try to schedule them in batches. for ex. unfollow 10 to 15 users - delay 18 to 29 minutes - unfollow 10 to 15 users.....
Hope that helps.