I dont think it is possible to delay the sending of an email within Hotmail by itself.
The way I would do this would be to use an email client to send the email for you, using your hotmail account.
Thunderbird is a free email client (open source equivalent of Outlook) that you can configure to use your Hotmail account. You can then use the 'Send Later' plugin for Thunderbird, to send a composed email at a date and time that you specify. Leave Thunderbird running on your machine until after the send date/time has passed.
CONFIGURING THUNDERBIRD FOR USE WITH HOTMAIL
1) Download and install Thunderbird from http://www.mozillamessaging.com/thunderbird/
2) Configure Thunderbird to use your Hotmail account: Tools --> Account Settings --> Add Account
3) Select 'Email Account' and click Next
4) Enter your name and full hotmail email address and click Next
5) Ensure POP is selected, then enter 'pop3.live.com' for Incoming Server (excluding quotes) and ensure 'Use Global Inbox' is NOT ticked, then click Next
6) Enter your full hotmail email address for Incoming User Name (eg joebloggs@hotmail.co.uk), then click Next
7) Leave Finish to add hotmail to the Account Settings list
8) Select Outgoing Server (SMTP) and then click the Add button
--- Description=hotmail
--- Server Name=smtp.live.com
--- Port=25
--- Use Name and Password=ticked
--- User Name=full hotmail email address (eg joebloggs@hotmail.co.uk)
--- Use Secure Connection=TLS, if available
--- Click OK
9) Select the hotmail account that we added earlier to the Account Settings list
10) Set 'Outgoing Server (SMTP)' to hotmail - smtp.live.com and Click OK
11) Select Server Settings, ensure 'Leave messages on server' is ticked and Use Secure Connection is set to SSL - click OK
12) Click the 'Get Mail' button. You will be prompted for your password. Enter it in the textfield and ensure that 'Use password manager to remember this password' is ticked. Click OK
13) Create a test email to another email address and click Send. Enter your password into the textfield when prompted and ensure 'Use password manager to remember this password' is ticked. Click OK
14) Check that the email is received at the other email address.
CONFIGURING SEND LATER FOR THUNDERBIRD
1) Tools --> Add Ons
2) Click the 'Get Extensions' link in the bottom right corner of the window that appears (this link will open in your default browser)
3) Enter 'Send Later' (without quotes) into the search field and click Search - 'Send Later 3' will probably be the top result
4) Click the Download Now button and save it to your desktop (the file is very small, so download will be almost instantaneous)
5) Select the (already open) Add-ons window and click the Install button
6) Select the file you downloaded to your desktop, wait for the countdown from 3 to 0 to finish, then click the Install Now button
7) After the installation has completed, click Restart Firefox and compose the email to send later
8) Once composition has been been done, select 'Send Later' from the File menu
9) Configure the date/time you want to send the mail and click the 'Send later at specified time' button
10) Keep Thunderbird open until the Send Later date/time has elapsed.