Thats a pretty big fricking leap...20 oz to 5 gal.

Too big.

But since you are done, realize your new soil has plenty of good nutes.

Let your eyes tell you when to start using ferts again. I would think about 3-4 weeks would be doable...but it all depends on your base soil.

Stopping the use of the nutes you are using will not harm them if you are starting with good dirt.