1. We will have to start this from the scratch;
To start from scratch = To do it all over again from the beginning.
2. If you need to refer to something, then this is the rule of thumb;
Rule of thumb = A broadly accurate guide or principle, based on practice rather than theory.
3. We are on the fence and we have to close this by the evening;
On the fence = undecided
4. He called up out of the blue and told me that he needs a new report;
Out of the blue = Something that suddenly and unexpectedly occurs.
5. I hope we are on the same page;
On the same page: When multiple people all agree on the same thing.
Doubts on this article