Even though you have not had symptoms, you can still pass the virus to others. You must still follow the ‘Self-isolation’ and ‘Ending Isolation’ advice as linked above.
The date your COVID-19 test was taken should be used as the first day of the 7 day self-isolation period. If you subsequently develop symptoms within that 7 days, then use the date of onset of your symptoms as the first day of your self-isolation period. The same date is used as the first day of the 14 day isolation period for your household members.