Squeeze juices fresh directly into the measuring cup or jigger. If you’re having a party, juice in mass the morning of. You will be able to make drinks more quickly.
The same is true with lime or lemon sour. I prefer 2:1 juice to simple syrup. When making only a few drinks, I will juice the citrus and ball park the simple syrup to get my 2:1. For parties, I make up the sours when I juice the fruit and make the simple syrup.
I do keep juices for a day or two, but you can taste the difference after a day.