numberoptions.delay is the time before reveal animations begin. By default, delay will be used for all reveal animations, but options.useDelay can be used to change when delay is applied. However, animations triggered by options.reset will never use delay.
{ delay: 0 }
The number passed to options.delay is a measure of time in milliseconds.
ScrollReveal().reveal('.logo');
ScrollReveal().reveal('.tagline', { delay: 500 });