Equal amount of time should be put into developing tests to validate or invalidate the idea. There's not point in doing any work if all the feedback you get is from your family, friends, etc., saying "Looks great I would totally buy this!"
That said, even before putting anything on the web you can easily bootleg wireframes in powerpoint and even add buttons that click through to specific slides as if it were a functioning product.
That said, even before putting anything on the web you can easily bootleg wireframes in powerpoint and even add buttons that click through to specific slides as if it were a functioning product.