I'd say so. At least, that's the age I'm using in the story I'm writing at the moment. And I think I remember asking about it before, so yes, about 22 is correct.
Of course, you can take into account that Lois was a Libra, so she could have started at the Planet just before she turned 22...maybe. That is, if she started sometime during the summer or early fall before her birthday. 21, 22... not that much of a difference.
Pelican