Predicting what time will a John go to the gym tomorrow? I have a data set which contains the below columns:

Name    Day      Start_Gym_Time   End_Gym_Time
John    Monday   16:00            17:30
John    Tuesday  14:00            14:42
John    Tuesday  15:55            17:40


I need some advice on how to predict when will John go to the gym next? I am planning to use scikit-learn for trying out various algorithms? Any help would be highly appreciated.
I would start by plotting some of the raw data. You might look at histograms of start times/stop times to see what the range of values are. You could also plot the start times as a time series to see if there are any long range patterns (i.e maybe as the week goes on John starts getting tired and showing up at the gym later).