you are only eligible for the second option if you are also making the first choice. You need to make both choices explicitly in your statement. In 2018 your days of presence for 2017 count as 1/3, so three months of presence in 2017 would count as one month for the substantial presence test. So you could file your return making BOTH choices or ONLY the first year choice after another 5 months in 2018.
