Have you grown before? If not, you probably don't need to flush. Just don't go crazy with multi-bottle "schedules," nor feed too heavily. Monitor your runoff ppms to see what the sale buildup looks like toward the end (how it changes from the start). You might feed half strength the last time or two. Add a little sugar (1/4 tsp/gal) to encourage the soil biology to make more nutrients available.
Hopefully someone who uses FF can guide you. I don't think flushing is necessary as long as you don't overfeed. I don't know how that relates to FF's schedule. (I get the impression people don't follow the schedule.).