If you drink on Friday will you fail a ETG test on a wendsday??

Maybe. But if you know you have a test on Wednesday why would you drink on Friday?

It's possible, but why risk it?

Is this your first test, or the first time you ever drank before a test? Why does that make a difference? Because drinking before a test is a dumb mistake, or you have a problem complying with the rules. Normally 4/5 days is enough to clear the body of alcohol detection, but many factors apply not the least of which are your drinking habits.

Unlikely that you would fail a test 5 days later, but it's possible. Anything is possible.

Why are you being tested? Are you court ordered to stay away from alcohol, or is this for a job?

Either way, I wouldn't risk it. Sounds like you have a lot of forewarning about the test. Much easier and smarter not to drink at all, then you don't have to worry about failing.