Ditto what everyone else has said; it varies by school. Research what is common at YOUR school. Joining your first term may be your best shot and you are sure to still meet women on your hall.
Also, at one school fraternity and sorority recruitment can vary drastically. I can think of several places where it's almost unheard of for women to pledge NPC sororities outside of formal recruitment (whether held in the spring or fall), but the NIC fraternities might have two different pledge classes, one in spring and one in fall. So rather than listen to your dad (well, listen to him, but take it with a grain of salt), research and find out what you can from NPC members.
