Please tell me how long it takes for to get in the deepest stage of sleep?

It differs: In the beginning of the night it usually takes between 30 to 60 minutes to get into deep sleep and 60 to 90 minutes to get into rem sleep. Every 90 minutes you should have a sleep cycle of light, deep and rem sleep. As the night progresses the amount of light sleep should get smaller and the amount of deep and rem sleep should get longer with the most rem sleep early in the morning.