Receive alerts for deadlines

We have multiple remodel projects running at the same time with similar tasks for each project. Is there a formula that would let us know that is time to order a certain item (flooring) or execute a specific task? Example: flooring takes 5 weeks from time order is placed and it would be great to get a notification/alert reminding us to place the order 6-7 weeks prior to deadline.

We are currently using free version, is upgrade to blocks needed?

Thank you.