I usually made the whelping pudding the first evening and let it set up overnight, served it the next day and the following day (usually gone by then anyways). I didn't like it sitting around longer than that.
Tea's first litter was 6, then 4, then her final litter of 5 (she's spayed now). I also supplemented with other calcium rich foods like plain yogurt and 4% cottage cheese. I never had to give extra supplements, but each dog is different
Wishing you a safe whelping and healthy, happy pups!
Debbie
(Tea', Katie & Paige)