I'm planning on taking 3 years off before pursuing an MPH to gain relevant work experience but am unsure what to tell one of my letter writers, a professor, regarding the timing of everything. They prefer to write the letter sooner rather than later, but because SOPHAS does not accept letters from Interfolio, should I essentially tell the professor to hold onto the LOR and have it on file until I apply for the fall 2018 cycle? Should I request to have the letter written by a certain date even though I'm not technically applying for this cycle (saying a date in 2017 seems too generous of a deadline)? I can't say I have a very close relationship with the professor, but because they are currently my only academic reference, it would also be ideal to have them write the letter while they still somewhat remember me from their class. Any advice would be appreciated, thanks!