I found that using this snippet leaves the cursor at the start of the date string, so I have to shift+A then enter to get to the next line to start typing. Adding +'put _' to the command inserts a newline so that you can immediately switch to insert mode and start typing.
ooh i get it, `alias did="vim +'normal Go' +'r!date' +'put _' ~/did.txt"` and this starts in insert mode. I like this. I think ill change mine to this.