mail.app – AppleScript to Schedule Emails for Specific Date

I am in the process of writing a small Python Script to automate sending some emails that I send every week, specifically every Monday at 8 AM. The Python script calculates when the next Monday will be, fills in the email template with the specific information, and then schedules it. I have been able to get the AppleScript to create the email, put in the recipient, and put the signature, but I have not been able to get it to click on the schedule to send email button and schedule it for 8 AM. Here is the current AppleScript I have:

 tell application "Mail"
        set theSender to "{sender_email}"
        set newMessage to make new outgoing message with properties {{subject:"Interest in {position} at {company}", content:"{email_body}", visible:true}}
        tell newMessage
            make new to recipient at end of to recipients with properties {{address:"{recipient_email}"}}
            set sender to theSender
        end tell
    end tell

    tell application "System Events"
        tell process "Mail"
            set frontmost to true
            tell window "Interest in {position} at {company}"
                click pop up button "Signature:"
                delay 0.5
                click menu item "AccountName" of menu of pop up button "Signature:"
                
                -- Wait for UI to update
                delay 1
            end tell
            
            -- Access the menu directly through menu bar item name
            -- This uses exact menu hierarchy: Message menu > Send Later...
            tell menu bar 1
                tell menu bar item "Message"
                    tell menu "Message"
                        click menu item "Send Later..."
                    end tell
                end tell
            end tell
            delay 1
            
            -- In the schedule dialog that appears
            tell sheet 1 of window "Interest in {position} at {company}"
                set value of text field 1 to "{next_monday_formatted}"
                set value of text field 2 to "8:00 AM"
                click button "Schedule"
            end tell
        end tell
    end tell

Everything works but the scheduling part, and this is the last attempt I have made. I know that there are email automation tools, but I want to learn how to code this by myself and integrate it into the terminal. Any help would be appreciated, thanks!