My surgery team don't have us starting supplements until 4 weeks post surgery - they then sent me a letter and a copy to my GP saying to start taking vitamins, iron, calcium and starting b12 injections. (i take a Boots a-z multivitamin)
With regards to taking pills though, i was only on iv meds for the day of the surgery and the next day they had me straight onto tablets, even the bigger ones like paracetamol. I was a bit nervous but they went down without a problem.
Each team is different so speak to your surgeon to be sure.