It depends on your wood frames and how you want your curtains/panels to cover your windows. If you're talking about a standard box 48" window, I'm guessing a couple of inches beyond. I wouldn't go too much further beyond unless there's an architectural or functional reason to do so. If you want to just cover the wood frame, then position the rod so the curtains hang along the wood frame piece.
It's all in your envision of the finished look. Post a picture of your window if you want something more specific.

Thanks for the reply. I had seen some internet advice written that said the rods should be long enough so when the curtains were open they should be off of the window. I haven't done it that way in the past, the rod has always been just a few inches wider.

I watched a Pottery Barn video on how to properly hang a curtain rod and it recommended 3 inches beyond the frame. That is exactly how I did it and it looks great.

It depends on the stack of the drapes and whether you want an open view when they're drawn back.
I extended the rod on a couple of my windows as far as a foot since the drapes have a wide stack. I like the windows fully exposed when the panels are drawn open.

I also extend the rods as I like the windows fully exposed when the curtains are open. The more light the better!