There are many variables, you should spend as long as needed, it's not a race (at least not at this point of the shave.)
Hard water slows it down, hard soap is different to creams, badger brushes can be quicker than boar brushes.
I had to follow this advice to get good lather from a puck of soap:
How to make great lather from a soap ~ Tutorial - Badger & Blade
(From: Lather Help. )
Alternatively this sounds excellent:
http://straightrazorpalace.com/shavi...tml#post319377
:gl: