BBT Scenario Thought

In BBT(Buyer Buys Trace) system which based FP-Growth algorithm, there is a transaction matrix necessary first, but the original scenario for this algorithm is shopping cart analysis, and all the stuffs in the cart composed the pattern, then counting each cart to generate the frequent patterns, finally, retrieve the patterns which are satisfied minimum support and confidence, you will get the predict table. In my scenario, there is not a cart for each shopping-time, so I assumed that the shopping cart is a period for a week primely, but I realized that is not exactly, how can I determine this period? maybe I can separat the whole shopping process into many sub-process according to the buyer's purchase customs, if his buys is repeat then the process terminated, another process conituning, but the time axis is also consideration, it is very important, the Markov Chain is a classic model for events predicting according time axis.