If the other two suggestions do not help you, rather than apply between Keyframes, you can also cut the Clip (Razor Tool) and apply where needed. If you need the "ramping" effect of the Fast Color Corrector, then just add a Cross-Dissolve. This works for other non-Keyframable Effects in many cases.
[Edit] You might want to Alt-click the Video to unlink it from your Audio, when using the Razor Tool. No sense in cutting your Audio too - in a very few instances, this can cause little "pops" in the Audio.
Hello Eddie, Ann and Hunt,
Thank you so much for your replies. I am very sorry for this late response. It's because I've been away from my computer because of a sudden health issue. I have not been able to try out your suggestions but I will soon.
Hope you're feeling better.
You will find the tutorials very instructive. Be sure to watch them all.
Best of luck. Hope that you are able to report back with success stories.
If you get hung up, or any of the tutorials doesn't quite make sense, please just ask. Someone here is very likely to have written that tutorial, or knows it well enough to fill in details.
See ya' when your Projects done!