bad luck: banks are closed over the weekend and monday is a holiday. By tuesday the new tax will already be in place and the respective amount in all accounts frozen.
There is still the danger of a continuing bank run come Tuesday. There is not enough cash to satisfy it all (and probably no willingness to let it be transferred electronically), so expect more emergency measures.
More likely they'll take the hit now, then if the crisis passes, launch lawsuits against the government to claim it back. Or a political party will adopt a manifesto pledge to return the stolen money upon election victory.