How often does a Ponytail Palm flower
It is uncommon, but not rare for a potted Ponytail Palm to flower, especially when kept indoors. It will flower very sporadically with no particular flowering cycle.
For more frequent flowering keep it very potbound and do not disturb the roots. Allow the soil to dry more than usual in the fall for about a month or so and provide cooler temps in the 50-60 degree range, if possible. Of course, it should also be kept on a moderately sunny windowsill year round.