You are able to exclude Future Starters from Queries by filtering on Start Date, as below:
If it's before a specific date, you can set the filter on Start Date: Less Than: Specific Date.
If the date is not specified, you can set the filter on Start Date: Last X Days [1000 days is the limit].
If it's just on the employees who has a starting date just before today, you can set the filter on Start Date: Before (Days): 1.