The rules were simple enough. For starters, I couldn't changed 'fixed points', such as say, the night of Nora Allen's murder. Doing that broke the universe, and created Flashpoint.
So, I've decided that I'd implement myself into their lives when they were around my age. The Doctor gave me a bracelet that allowed me to change my size so I could be younger. Physically and mentally, I'm 11.
The first universe we went to was the world of Power Rangers and Super Sentai.