1) idea
2) write & code
3) peer review & test
4) implement
5) tell people about it
Out of curiosity: What is the difference between 2 and 4 in your list?
2 would be a reference implementation, in Python for example, and 4 would be the actual implementation.
OK, but then strictly speaking, you would need another test phase after 4 :-)
I'm pretty sure Satoshi, told people about it, wrote a paper, wrote some code, implemented it, pissed off.