It can be years to never. Being shy can also lead to severe anxiety and complete locking up to the point you cannot even talk to them without stuttering, going blank or hyperventilating. Since that is so embarrassing and hard to over come, some guys simply avoid the whole situation totally, and therefore never ask the girl out.
It will take him as long as it takes for the girl to start dating another guy and then the shy guy will just give up. But then he'll learn a valuable lesson on taking risks and will ask out his next crush.
You need to poke him with a stick (figuratively or literally)...freeemoticonsandsmileys.com:10080/.../...0poke.gif Shy guys need some coaxing if you really want to get together with him. You need to initiate conversation with him or wait next to never as someone else suggested.
Oh ya this was me at a point because I had trouble asking my crush out. You need to first become closer to him like text him and talk because once I got comfortable around her I just went for it and asked her out and she said yes. So basically just try to get to know him better. If that doesn't work ask him out yourself
Not long if you help him out and ask him to take you on a date. You're not asking him out, but you're telling him you want him to take you on a date. So for me it wouldn't violate that unwritten rule of girls asking guys out!