Your icons are indexed in the search results shortly after submission. The process is automated, so you will just need to check again at a later time. If your icons are properly tagged, they will begin appearing in searches based on the specific tags.
Newly uploaded icons might not be easily discoverable simply because they are recent and don't have downloads. This means that a good practice is to promote your new icons on your own channels, in order to make them more discoverable for customers and start getting downloads.
Newly uploaded icons are not categorised immediately upon submission. This, however, is a manual process. It is just a matter of time for them to be assigned to a category by someone from our Content team.