How do I adjust the amount of time my electric choke on my Edelbrock 600 is on? It stays on for about 3 or 4 miles. Or is that normal??

Normally it takes a few minutes for an engine to warm up with a carburated engine, electric or manual choke......
You can drive a vehicle as soon as you start it but it is extremely hard on the engine, fuel milage, and clutch/or automatic tranny....:skull:

I do let it warm up for 5-10 minutes before I leave the house

***Edit***
and I plug in my block heater and oil warmer every night

You probably have a bad heating element in the choke housing, or your losing power to it...
You can buy replacement elements from Summit......:skull: