I graduated with my masters in May 2017 and I will be applying for a Ph. D program for Fall 2019. I want to ask my Masters professors for letters of recommendation but I don't want to bother them too early about it. However, since I graduated a while ago, I'm worried that as more time goes by, the less likely it is they'll remember me. I would like to know if now is too early to ask for a letter.
Tldr: When is the appropriate time to email professors for letters of rec?