I'm currently a certified trainer through ISSA. I would like to add a nutrition cert but i cant decide. The one ISSA offers looks great but so does precision nutrition. I know they are similar because both are by John Berardi but the precision cert seems more fine tuned. And precisions next certification doesn't happen until next march. Whereas, I can start ISSA now.
have you looked at NASM Fitness Nutrition Specialist? I took it a while back and liked what they provided in terms of textbook and online material. It goes into a LOT of detail.
Now you have three to choose from. Go with your gut and the one you like better; try not to worry about the time frame. What's a few months for what you believe is a better course?
Take care, Danny