While your friend is well-meaning only you will know when the best time is to start dating.
There is no prescribed period in which one must start dating post divorce. Only start when you feel ready.
Remember, DATING doesn't mean you will be jumping into a committed, long term relationship. Dating means that you will be wined and dined, that you will meet new people, that you will have some frustrations and that there will be good stories to tell.
When you are ready for that, start dating.
Take your time, don't rush things. Don't make the same mistakes twice.