For year 2017, I was on F1( I hold F1 for less than 5 years so far) and doing my OPT. I also applied H1B, but my application was pending on the last day of 2017 and is not approved yet. 

So for tax year 2017, should I file as non resident alien or resident alien? If  non resident alien and if I receive more than 100K in 2017, should I file 3520?( I heard that if you file 1040NR as non resident you don't need to file 3520, will my appliction for H1B alter this rule?) Will it be any downside if I just go ahead file the form when I don't have to(as non resident alien) or when I am not sure if need to?