The first planned services are for the morning of the 4 January. Even if they finish early, its unlikely that there will be enough time to organise drivers and station staff. There would be a limited number of trains run before the in-service trains to ensure things have bedded down properly and tolerances checked.
The curve is tight enough - only a few hundred metres radius. Much tighter than Dalkey Tunnel or most of the curves in the city centre, save maybe Newcomen Curve.
http://maps.google.com/maps?f=d&sour...,0.016544&z=16