Currently 21 weeks pregnant and starting to buy baby items. I'm looking for a steriliser for babies bottles and I will be formula feeding. I don't really understand what the point is in sterilising multiple items at once because guidelines say you can't make up powder formula feeds in advance and as soon as you open lid it's introducing bacteria so can you only really sterilise one bottle at a time? Am I missing something? It's all so new and overwhelming.