It all depends how you grow it on after rooting.
I put mine in pots and I can get a good size plant in 12 to 15 month. You will have to increase the size of the pots every 3 to 4 month whenever the roots hit bottom.
Remember that some varieties are slow to root.
If it takes 6 weeks or more I do not try this variety again and it has to be budded to an understock.
If it roots in 3 to 4 weeks it will be OK.
Check out this follow-up post of mine on the MINI FORUM

Here is a link that might be useful: Planting NEW Minis

For me in my zone most of my rooted babies take 1 year to become a grown specimen. You can't tell the 1 year old from the oldies. I know some may be a bit slower but I just haven't noticed.

WHen we were designing this garden we planned for only one Red Cascade. At the last minute we decided to put in an arbor and needed two. I rooted the second one. The designer laughed at me when I brought the rooted baby with the 2 gallon 2 year old Red Cascade. WIthin One year you could not tell which was which. This is picture is from year 3 and you sure can't tell.

FYI the one on the right is the little rooted stick I planted.

Thank you both for the feedback.

The Red Cascade is impressive. Was the purchased Red Cascade an own root or a grafted plant?

Own root.