Function interval_at 

pub fn interval_at(
    start: Instant,
    period: Duration,
) -> Result<Interval, IntervalError>

Creates a timer that emits events periodically, starting at start.

When throttling is activated (i.e. when using a non-0 wait duration in Context::acquire), timer entries are assigned to the nearest time frame, meaning that the delay might elapse wait / 2 ms earlier or later than the expected instant.

Use interval_after_at_least when it’s preferable not to tick before the expected instants.