In order to remember information for a long time, it must be repeated as soon as it is on the verge of forgetting.
Repetition intervals are calculated using the Ebbinghaus forgetting curve. There are aproximate intervals recommended between repetitions: after 1 minute, after 30 minutes, after 2 hours, after 8 hours, after a day, then after 5 days, 3 weeks, 2 months.
The intervals may vary for each person individually.