My vote is for performing the weekly water changes during the startup period. IF your fish load is "light" then 10%/week should be sufficient at this stage. Later you can increase as the need arises. I usually tell our customers to wait to backwash their Ultima filter for the first TWO WEEKS. However, other routine maintenance should be done weekly. After two weeks, begin your normal routine on EVERYTHING! Also, on a personal note, I use a Ultima 20000 on my 10,000 gal pond for mechanical purposes, so I don't really concern myself with bio output. Whatever it gives me is a bonus anyway. I backwash once a week during winter and two to three times per week during warmer summer months. Someone once made a suggestion to me and it has proven to be true for the last 10 years - whatever maintenance regimen you employ, stick to it. Do not waiver from it. Yes, you can increase or modify in the early stages if you find the need to, but once established, keep it up religiously.
Mike