I am sorry but B.Arch doesnt have lateral entry unlike B.Tech. You have to join the first year and hence it cannot be a lateral entry. The confusion comes from diploma holders who assume that it is just like B.Tech where admissions are allowed in the second year ie 3rd semester. That is wrong. There is no lateral entry. Admissions are to the first year B.Arch programme. However, diploma holders are eligible to apply along with 10+2 candidates. So you can choose any college and apply.