The way I did it back when I had no remote to trigger: Place some dummy object to focus on, start the timer, then run and replace the dummy with yourself. I'm sure you've got something lying around that you can use for that purpose. Even if it's just a broom leaning against a chair.

That of course is just a workaround to get things done. If you're doing that more often, you should definitely consider getting some sort of remote control for you camera. There are quite cheap wireless transmitters from china on Amazon that work well with rebels and can also be used to fire strobes.

And since J0hj0h mentioned, that the wireless transmitter wouldn't fix the issue of the blurriness: it does, if you choose a transmitter that allows to set the auto-focus, just like pressing the shutter on the camera itself. Using that, you can even use lower f-stops. Just not too low, because in my experience the auto focus often takes the nose to focus. This creates a little blur on the eyes, which generally should have the main focus.