urgent, question about blood stool samples

Before i bring my stool sample STAT into the hospital (it has to be there under an hour) i need this simple question answered:
I'm doing the fecal occult blood sample, to test if there is any blood in my stool. The problem is i only have massive rectal bleeds once in awhile, it doesn't happen all the time. So i'm wondering, do i wait until i have a huge bleed to collect the sample, which there is no way to calculate when, or will they be able to pick up on something when my stool is normal without blood?
I just really want them to figure out what's wrong with me, and im scared that if i don't want until it's bleeding, they won't find anything. Should i be getting these stool tests done regularly, considering my stool consistently changes?

[Kaneda2112]

The Fecal Occult Blood Test is typically used to see if you have hidden bleeding and they can be done anytime. Typically they want to see a series of samples. They want to see if you're bleeding at times other than when you can see it. Blood that you can't see is typically but not always more of a problem.

Your current problem could be something as benign (but irritating) as hemorrhoids or potentially something requiring more investigation with a colonoscopy or other methods. I know it can be extremely difficult, but it's best not to think about this too much and take the results as they come.

Here's a quick review of the stool test from wikipedia -

"Fecal occult blood testing (FOBT), as its name implies, aims to detect subtle blood loss in the gastrointestinal tract, anywhere from the mouth to the colon. Positive tests ("positive stool") may result from either upper gastrointestinal bleeding or lower gastrointestinal bleeding and warrant further investigation for peptic ulcers or a malignancy (such as colorectal cancer or gastric cancer). The test does not directly detect colon cancer but is often used in clinical screening for that disease, but it can also be used to look for active occult blood loss in anemia[2] or when there are gastrointestinal symptoms.[3]"

Your doc will let you know how often the test is required or what actions (if any) will be required next. I'm surprised your doc didn't use an anoscope to have a look in the first 4-5 inches of your colon to check for issues. That can be done in most doctors offices.