This is what I have. Am I right?.
SELECT
a.data_date
,count(case when serv1 = 'N' and serv2 = 'Y' then cust_id else null end) as from1to2
,count(case when serv1 = 'N' and serv3 = 'Y' then cust_id else null end) as from1to3
from tableA A
left join tableA B on A.cust_id = B.cust_id
and a.data_date = dateadd(mm,1,b.data_date)
group by a.data_date
order by a.data_date