Well Logan - 5 months is still facing the rear however I turned Sophie now 19 moths when she was about 8 months.
Some may say it's too early but you should generally know when to turn your child around as they will let you know.
Sophie used to try and turn her head around to see us and would always be quite cranky when we put her in her seat, she would always lean forward as if she were about to leap out of the seat!
I guess try to keep in the rearward facing position for as long as you can because it is by far the most safest but if your child is insisting on turning around then make sure that your little one can strongly and firmly hold their head upright.

Hope this helps!