The books i use to read before i started into marine aquariums encourage the use of a refugium as another route into the hobby and i was intrigued. All my tanks always have a refuge with lush algae growth and a haven for small aquatic creatures. The benefits of a refugium can be substantial if done correctly.
Many hobbiests have a way different outlook on the term "cycling"
If you are stimulating a cycle and your aquarium's parameters are NOT within acceptable range then I would wait until the cycle is completed. ie: high ammonia / fluctuating nitrite and nitrate levels.
If you are "cylcing" with established rock and your aquarium's parameters are within acceptable range - then go for it.
Some will say - whats the difference?
Chaeto is easily replaceable but other macros are much more sensitive to changes/fluctuations and seek higher replacement costs.
Not sure what your experience is with reef keeping, but if you are new - the best advice i could give you would be to take it slow and get use to daily/weekly/monthly maintenance ie: testings-water changes-topping off so you can get a nice stable envirement for whatever you choose to add.
Thank you for the feedback! I'm actually upgrading from a jbj28 to a 65g deep blue with a 20g sump. New to the sump world yes lol trying to get as most knowledge as possible. Don't want to make too many mistakes as we all know this hobby can be pretty pricey