Adding days to dates
visits_wd['label_time']=visits_wd['last_date'].map(lambda x: x-relativedelta(months=goback))
df_test1['add']=pd.to_timedelta(df_test1['add'], unit='D')# convert integers to days this way
df_test1['forecast_date']=df_test1['forweek']+df_test1['add']