Yup... if you don't add fish right away, then you're going to have to keep adding something to create ammonia. Most folks sprinkle fish food in their tank every few days. Only problem though is that you're just not going to know how much to sprinkle.
Just my opinion, but there's no real reason to start up the tank that early if you don't intend to stock it for a while. No reason to give the bacteria you've built up a chance to die off.
Here's what my "perfect" startup plan would be - if you had all the time in the world...
1. Get quarantine tank set up and throw in a cocktail shrimp to cycle.
2. Once quarantine tank is cycled, fill up the display tank with salt water and add your rock, and then your sand bed.
3. Give you display a couple days to clear up and then add a cocktail shrimp to start the cycle.
4. Go to LFS
and get your first fish and put it in the quarantine tank.
5. Let display tank cycle, all the time checking ammonia/nitrite/nitrate levels.
6. If the display cycles quicker than the minimum 4-week quarantine period, then keep the bacteria in it alive by adding a pinch or two of fish food every couple days.
7. After the tank has cycled (assuming it's longer than 4 weeks) transfer the fish from the quarantine to the main.
8. Go to LFS
and get your cleanup crew, and your next fish! Put cleanup crew in display and fish in quarantine.
Basic point is that you really want to get your quarantine tank cycled first so you can have a fish in it while your main tank is cycling. If your main tank takes longer than the normal 4-week quarantine period, no problem... your fish can just hang out longer in the quarantine tank.
And don't tell us a quarantine tank isn't in the budget... we know you're springing for LED
lights on this bad boy!