I recommend you to reject it, and withdraw your EE profile for now.
The ECA number doesn't matter. It will be your WES ref number + IMM. However, in the form it asked you for report completion date, and you lied (sorry, but true) here. Should you submit Ontario PNP application or if you got invited tomorrow, you could be interpreted as misrepresentation (remember when you submit EE profile, the system asked you to confirm all information is true and correct). You will face a 5 year ban if found misrepresented.
Simply put, it doesn't worth it. You could just wait for a few more days to enter the pool, and avoid all these hassles.