The international drivers permit is, essentially, a translation of your real drivers license. It is meaningless if you don't have your real drivers license with you.

It is only good for a year. I'd say wait until you have an international trip planned, then look up the destination country's regulations to see if they require an international drivers license. IF so, get one then. If not, skip it.

Personally, I don't bother if I am going to a country where the native language is in Latin script: France, Germany, Italy, Spain, etc. I would get one where the native language uses other characters: Japan, Arabic countries, China, etc.