Hi and

. A male goldfish will have white pimple-like things on his gills and pectoral fins around springtime. A female fish will enlarge with eggs and the "opening" will turn outwards.
Here is a link. If it is pregnant, then it should lay eggs pretty soon. Is there a male fish around? If not, then he will not be able to fertilize them when she lays so you shouldn't worry. If there is, the hatching time will relate to water temperature. Here's another link:
Breeding goldfish. Hope that helped some.