CFC Question- Copper/Coil LENGTH

I have built out a CFC with brass fittings; havent tested it yet but I ended up going with only a 20 foot length of copper tubing. By the time I cut a couple inches off and have the 4-6 inches coming out of the hi temp hose, I have a good 19 feet.

My question is, with my water temp at about 68 deg F, will this be enough distance to chill the boiled wort down to 70 deg? Should I use my IC first, then change over to the CFC, or use the IC in an ice bucket prior to the CFC?

What do you all think?

Yes, I think I am over thinking all of this, but then again its what makes this hobby great.

My friend has a short CFC, maybe 22 ft. and it works just as good as my 25 ft. I don't know if you'll get down to 70F, but certainly down to 75F. Running your cooling water through the IC in an ice bath is not a bad idea, and most likely you'll need to throttle back your cooling water or you'll get 55F wort!