Q.When Does A Bird Of Paradise Plant Usually Flower?
I have just taken my Bird of Paradise flower (which is about 8-10 years old) in to my garden room from outside on the patio. It does look healthy with about 10 leaves and 2 more shoots in evidence but has not flowered for last 2 years.

Certified GKH Gardening Expert
Likely, this is a lack of phosphorus and/or potassium. Both play a critical role in flowering. Feeding isn't mentioned, but that is important for healthy growth. I would recommend a fertilizer that is either 10-10-10 or a slow release 20-20-20, according to the instructions on the particular brand you choose.
Make sure to test your soil, first, for pH and nutrient imbalances before feeding. This will give you a better idea of what your plant needs.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm