Hi
I asked this very question to the DLP help team on Twitter a couple of weeks ago and was told " there is no opening day as yet, keep checking our website for details". The only problem is that the railroad closure isn't even mentioned!
I would suggest that you keep checking the website and the app to see if any updates are posted.
I know this is probably not what you were hoping to hear. Enjoy your trip to DLP.
TTFN