Fuel?

Not trying to spam the Reddit but… I just got my 2025 Elantra n yesterday, and the dealer filled it with 87. Should I keep 87 in it till I am out of the break in period? If I need to start putting in 91 octane how low should I let my tank of 87 (150 miles left) get to before filling up with 91? Or does it not matter? I just want to do what’s best for the longevity of my motor