Rollover api : How to Run it 30 min wise

Hello can anyone make me understand this regular expression for roll over api:

PUT /<logs-{now/d}-1> with URI encoding:

PUT /%3Clogs-%7Bnow%2Fd%7D-1%3E

Now if I want to have netflow indices of format netflow-2018.08.10 rolled over, what do I do?

From theory, I was told that roll over api works with the format of having it ended with an integer -1 like netflow-2018.08.10-1 and then make an alias. The alias will be rolled over.

However this thing is not working and I am really struck on what to do next.