By default, IDN sends email notification whenever an account is created. If you are using that OOTB email templates then I don’t think you can schedule that. However you can control them through your HR Source aggregation schedule if user account created as a birthright. if it is manual request, no one will place a request after office hours rite.
You can disable this OOTB account creation email notifications.
Yes workflow has that limitation.
Alternative is, you can create a Powershell script and schedule it in your IQ Service server in such a way that emails are sent within some intervals of time.