I think there are lots of good ideas here, but I am stubborn and wanted to see what it would take for the bees to do it on their own with no cajoling.
I established the hive in May 2016. They filled the original (foundationless) brood box by the end of July and cast a mini swarm, which I captured and reintroduced along with another brood box (also foundationless).
In October the two brood boxes were at 9 frames each and pretty full and I added the Flow Box, without and excluder.
In the middle of March 2017 they finally were ready to begin filling the Flowframes.
So, from hive establishment from a smallish swarm, in May 16, to action in the flows in March 17, 11 months later.
This is in San Francisco, which has a mild marine climate, and year round flows of some sort.