I would think today (Tuesday). If they hold to what was said... any new additions after closing would be put on the T-Mobile network. ie... device too. Not sure if that helps. I would think any deal Sprint had would cease as soon as signatures are in place.
I'm sure we'll know more once the markets open... information will get generated. If the plan is actually in place to close tomorrow or not. I'm sure the banks wouldn't of been told to have funding ready for April 1st, if it wasn't really going to happen. We'll see. Might be a busy news day later?