Answer:
It is important to use what you have. An opportunity can be one of those things. But opportunities can come and go, meaning (depending on what it is) you may only have a limited amount of time to take advantage of them.
For example, a job offer. Job offers are open to the public, so you aren't the only one that will be applying. You can take time to think about whether or not you want this job, and how you would answer interview questions. If you procrastinate to do so, you could easily run out of time in order to accept. Then you are still left without a job, and without any opportunities.
Opportunities can come and go, but you should never count on one coming back or another one showing if you get one. As soon as you see an opportunity, go for it.