毕业于中国排名第一的综合性大学及理工类大学 is not factor that you should get gc appro

Obviously, a guy in my group got his gc recently after he got his Ph.D in UIUC about three and half years years ago, he attened Sichuan University (not the universities you mentioned such as Peking U and Tsinghua). It is your own (characteristic)not your college that makes a big difference to get gc soon or later.