Dear sir,
Upgrading Joomla from 1.5 to 3.2 is not an automatic process, and can not be done in one day.
Duration of process depends of size of a website, number of articles, components...etc.
the biggest problem, might be paid components that you do not have expired licence (and have to be paid again) or components that are not compatibile with Joomla 3 and you have them in previous version. Then its take time for me to find free/paid replacement...
During upgrading process to Joomla 3, your original website is fully functional.
I am applying to this project in order to continue and progress my career as a freelancer. If you require someone that is honest, reliable and extremely dedicated, I would appreciate if you hire me for this project. Regards, Milos