I would sooner die than marry you!
It had to be done sooner or later.
In this case, sooner is so much better than later.
"I owe you an apology for not telling you sooner," he added.
Sooner or later he always gets his way.
No sooner had he returned home than he began the work of accumulation, and records that, on the receipt of his first quarter's allowance, a large share was appropriated to his literary wants.