Operating Aircraft VS 300/301

Just booked LHR-DEL 29th Jan returning 9th Feb,showing as A343 outbound A346 inbound.

Does anyone know whether VS are opertaing a mix of aircraft on the route this winter,(I understood it was to be the A346 and at the moment is so on most days)or do they schedule maintenence etc so carefully that they make a change on certain dates.

Or is it possible that the website for certain dates has not been updated form the former A343 and outbound will in fact be a A346?

As with SFO this winter, operating a/c will depend on the loads - if they are light a 343 will be used rather than 346