Send email at future date and time

Is it possible and how to send email with future send date and time using object class CL_BCS. I was able to email using OO but it send immediately.

Now, I need to send email with PDF attachment to a customer at future date and time and there is FM SO_OBJECT_SEND where you can set the send attribute in table RECEIVERS field RCDAT and RCTIM but I don't know all about the parameter in this FM to attach PDF format file. Does anyone have a sample? Thanks