Notification Trigger 44 Weeks After Date



I'm trying to set up an automatic notification for training reminders without using helper columns. I'd like to set up the trigger date as 335 days after a specific date (4 weeks before they need to renew). For example, if they renewed their training on September 28, 2020 then they would get a reminder notice on August 29, 2021...4 weeks before September 28, 2021. I can send automatic notifications 180 days after a date and 365 days after a date, but nothing in between those two parameters. Is there a way I can add my own "days after a date" parameter?

Thank you, Janette