First, read the owner's manual, They may use a break in oil that needs to be run for a specific mileage. Having said that, once you hit one thousand miles a first oil change under the guise that any manufacturing flaws that produced wear metals will be emptied, is viable. But if you went 3K miles, that should be just fine.
As for good oil, Mobil 1 synthetic, with Nissan recommended viscosity is very good. Some may think oil changes every 7,500 or so is too long, with synthetic changes every 5K miles is a nice interval. Much depends on your feelings about enviromental issues, and if you were to do oil analysis to make sure everything is OK on those long intervals.
Also check out Redline Synthetic oil, and some of the other extremely high dollar, high quality base stock, exotic oils, at about eight dollars or more per quart compared to three to four dollars for Mobil 1.
Learn to do the oil changes yourself.