How long does it take to convert XHTML/CSS to a WP theme?

Hey guys….. never done a theme before really & was wondering once you have coded a design into XHTML/CSS approx how long does it take to make it all work in WP?

I’m not building the theme for anyone else, it’s just for the one site. Ir’s pretty simple… has about 6 different pages in the nav mainly consisting of just text & a couple small other things like contact forms.

Thanks!