at/by the end of July, by August, by the time

[butdeptrai]

Hi!
Assume that we want to go traveling before August, not the beginiing and middle of July, it means that on one of the days from 23 to 31 of July we'll start the trip.
Please show me the true sentences, and explain to me why not correct!:

1/We should go traveling at the end of July.
2/We should go traveling by August.
3/We should go traveling by the end of July.
4/We should go traveling by the end day of July.
5/We should go traveling by the time July ends.

Thank you very much!

 

[EnglishFix]

1. Correct. This is probably the most common way to say this.
2. Not correct. This usually means "We should go traveling by the end of August."
3. Somewhat correct. The grammar is correct but people usually say "We should go traveling before the end of July."
4. Not correct. "The end day of July" sounds strange.
5. Somewhat correct. The grammar is OK but this is not how people would really say it.