I understood it to work out about the same whether you claim in the old year or the new year. If you claim the lump sum in the new year, then yes, initially you don't get much back compared to if you claimed in the previous year. But then all medical expenses from then on for that new year are a the 80% discount, so you end up with similar savings at the end of the day.

I'm glad I did ours at the end of last year tho.. coz the threshold went up from $750ish to $1000! So we WOULD have missed out on some money. hehe.