Why after 3/4 months, i never have understood the reasoning behind the strategy that an older account that has been idle for 3/4 months would be more trustworthy, if i was a engineer at IG that was the first red flag i would put on that account, because nobody creates an account to have it idle for 3 months and then start posting liking and following.
You don’t have to do three months anyway, one month is enough… start with liking and posting a view pics, just use fresh accounts and age then carefully, you WILL get PVed no matter what you do, aged or not aged as soon as you’re going to have increased activity on your accounts changes are 95% you get a PV.
Here is a schedule that i work with
Day one profile and bio update (No Link yet)
Week one 10/30 likes a day 3 picture posts, follow some leaders in yoru niche
Week two, follow 3/5 people a day 30/60 likes a day 10/15 comments and 4/6 picture posts a week
Week three follow 10/15 people, 75/150 likes, 20/30 comments, 1 picture per day
Week four add link get PV start following 50/60 people a day 75/150 likes, 20/30 comments, 1 picture per day
And then i start increasing the following with a 100/200 followers per day, like and comments i keep the same, especially comments as still don’t know how to work them
And you keep on gradually increasing until i am at 500/600 followers a day.
That is how i do it and i have lost a view accounts, that will happen anyway, cost of doing business, but i don’t spend money or time on aged accounts, its a hyped thing created by account sellers, and yoiu know how it goes, some guy in a forums states that older accounts are better and everybody believes that idle accounts of three months old don’t need a good warming up. And then they wonder why their shit gets banned all the time 
Goodluck.