ZeeRX350

I'm a newbie to this website. I'm at 1,000 mile w/ my RX. The dealer says to change at 1,000. Is it necessary to change it then? My mechanic read in his "book" (about everything you need to know about any car - or something like that) to wait until 5,000; that it was filled w/ synthetic oil at the dealership. Who waited until 5,000 mile for the first change? I really don't know didly about engines & want to do the correct thing! I'm planning on driving this RX for a long time.