Marinate for at the very least 20 minutes but the longer the better! Basically the longer you let it marinate, the more flavorful it will be! You can marinate it up to 2 days.
For the 6 tablespoons of fresh parsley, you can sub 6 teaspoons of dried parsley.
You can substitute dried oregano for 1 1/2 tablespoons of fresh oregano, minced.
Lemon juice concentrate is a fine substitution for fresh.