Lead time in NeetoCal sets the minimum notice a client must give before booking a meeting. If your lead time is 12 hours, clients cannot book any slot that starts within the next 12 hours, which prevents last-minute bookings you might miss.
Many people choose a lead time long enough that no one can book a same-day meeting after they check their calendar in the morning. Others, such as online therapists who are usually at their desk, set it to zero so clients can book any open slot right away. Choose a preset lead time or enter a custom value in the Where tab of each scheduling link.