I follow Andreas Moritz and do at most 4 minutes. Start with seconds and then minutes. You will be amazed how you can just walk around with oil in your mouth. I must say I carry a papertowel just in case I can't hold it.
and then I usually swish my mouth out first with some water etc ...
Then I OP for usually about 10-15 mins then do another if I'm so inclined. At about the 10 min mark I feel that my oil is about all used up. Shoot for 10 mins if you can and then either do it again or do it again later in the day.
It's no big deal, I do it while I surf the internet or watch a movie, I lose all track of time so it just flies by. I don't let the oil get on the back of my tongue so it doesn't activate the gag reflex.