If you want Oraclize to execute your query at a scheduled future time, just specify the delay (in seconds) from the current time as the first argument.

Here is an example:

oraclize_query(60, "WolframAlpha", "random number between 0 and 100");

The preceding query will be executed by Oraclize 60 seconds after it's been seen. So if the first argument is a number, then it's assumed that we are scheduling a query.