African jasmine is a common name that needs checking. Confirm the plant's identity before using a promised flowering age or calendar to judge a non-flowering specimen.
Confirm which plant you own
African jasmine is a nursery common name. It should not be assumed to mean the same plant as Arabian jasmine or another Jasminum species. Ask for a botanical label before comparing flowering information.
Flowering depends on plant identity, maturity and growing conditions. A claim that every plant will bloom after five years, or within one particular month, does not provide a useful test for a specimen grown elsewhere.
Review growth before changing feed
Inspect the light reaching the foliage and the condition of the root environment. Review recent pruning and any changes of position. Healthy leaf growth can be worth maintaining even while the plant is not in flower.
Use a suitable feed only when appropriate to the identified plant and its growth. Extra phosphorus is not a guaranteed way to turn a non-flowering plant into a flowering one.
Related reading: African Jasmine Care: Confirm the Plant and Growing Conditions.