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.
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