I've built an entity set and one of the tables in this entity set is called "inspections". I've set the time_index column for this table, but when running dfs, I'm getting the warning "Using training_window but last_time_index is not set on entity inspections". The documentation shows that this should be set as a series: last_time_index (pd.Series) – Time index of the last event for each instance across all child entities.
Can someone please provide an example of how and what values I should set the last_time_index to?
Note, the calculations are still correct, but I'm concerned about the warning message.