You may be able to do both. Let her learn on a 250. When she is ready, let her upgrade to your 600. Then you can upgrade using the $ from selling the 250 as a down payment. Fwiw, when my mom learned how to ride, she learned on a VLX600 cruiser. She ended up upgrading about a year later to a 750. The small displacement vtwin cruisers don't have a lot of power.