I think this is most likely. Labour will be perfectly prepared to fill the budget with as much short-sighted, sugar-coated economic suicide as possible to win over as many gullible voters as they can. An election ASAP after that (wouldn't do to let people actually have time to THINK about those policies) under the banner of just being sensible does indeed suggest 6th May. This would also go a small way to avoiding looking like they're hanging on for dear life till the end, at the expense of one measly month.