There isn't much they can take to begin with. They can have infacol straight away, but no point getting that unless they get colic and they need to be 4 weeks for gripe water. They can't take calpol until 8 weeks, and need to be 12 weeks for ibruprofen. Saline nose spray is useful for colds, but not sure how old they have to be until they can take that.
I find oral syringes easier getting medicine in and accurate than a spoon and you can get from pharmacist for penny's.