Travel outside country and H1B Visa Stamping after premium processing approval (F1->H1B)

[optidude]

Hello,

 

I am on F1 OPT STEM period valid until Dec 2015.

 

I am curious as to whether it is advisable to get H1B stamped immediately after premium processing approval (say in July/August)  with H1B start date of Oct1st. Will I be able to enter the US (after travel) with H1B stamped in my passport but on F1 OPT status and wait for the COS to take effect on Oct 1st? Will there be any issues either during entry or for COS to take effect on Oct1st if I have H1B stamped prior to Oct 1st.

 

Thanks,

 

AVE