Hi Abhishek ,
Nice to hear that want to be in SAP domain , please start looking into SAP SD first , since you have some functional experience, which help in future , once you complete the SD training .. Try to start working in SAP SD ,
Since SAP is big domain, while working you come across all other modules which you may interested to learn and pursue your career,
my suggestion would be since there is no hard and fast rule you have to do these and these modules,start with SD and move forward while working learn other module as your projects demands,
Wish you all the best ,
Thanks
Shakeel M