When Does The Clock Start Ticking On A "Non Immigrant B" Visa?

[nietzche]

I have a contract to begin teaching at a Thai university on May 1st. I will be receiving all of the paperwork necessary to go to the Thai Embassy on April 15th. If I apply for the "Non Immigrant B" before the start date of the contract (May 1st), will the Visa begin on the date I go to the embassy, or the contract start date? Thanks in advance!

[lopburi3]

A single entry visa is valid for 90 days from date of issue for entry into Thailand. Upon entry (use) a 90 day stay from that day is provided (day of entry is day one).