How do I add people into a campaign mid-campaign?

I run a mortgage business in Canada and here we have terms, 1 year, 2 year, 3 year, etc… When the mortgage closes today and I tag them to a 5 year campaign, the field timer will begin based on closing date, pretty simple in this case. However, I have recently migrated my database into Infusionsoft and I would like to add my existing clients to various campaigns. Let’s take the same 5 year campaign I mentioned earlier…how would an older client enter the campaign mid-campaign? The field time only allows a max of 365 days, which works for client no older than 12 months. I was hoping to go beyond 365 from date of closing…400, 450, 500, 550, etc… Why this is important is that in the last year of the campaign I have a series of email following up on renewal at 9 months prior, 6 months prior, 4 months, etc… Any help is greatly appreciated.