My therapist, who is exceptionally wonderful, takes into consideration how long you think is right. If she talks to you, finds that you are communicative and rational and are capable of making a decision such as this, she will give you a referral to an endocrinologist for T. Basically, it's "I believe you are in a place in your life in which you will be able to reflect and communicate about your feelings", and that goes for starting T, too. If it's the wrong thing, she expects that a communicative, rational person will be able to tell, I suppose. In my opinion, a little extra caution isn't horrible, but you are, I assume, an adult capable of making these decisions for yourself.