Playing a Day One - Mental tips/General advice/Stack Goals

This weekend I am registered to play a longer live NLHE tournament than I am generally used to. Although I'm relatively comfortable with a 6-7 hour online run, and a 4-5 hour live run, this weekend is a step up for me.

The tournament is at my local casino and Day 1 starts at 7:30pm. The structure sees all players play 14 (30 minute) levels until completion. Day 2 will resume a few days later on a mid afternoon. There are multiple flights and the player pool is quite varied with several local casinos offering day ones.

Buy-in: £100 NLHE MTT, 30,000 starting stack. Level 15 (start of day 2) is 15,000/30,000 BB ante - 7,500.

I was hoping to gain potential advice for this tourney. I am happy with my strategy and game, but I am a little unclear on my stack goals and mental preparation. For example, should I try and spin a 15BB stack around level 12 if I am low? Should I lock up a big stack early? I am a little confused as I have never actually made a day 2 before. Previously, I have loosened my game too frequently as I have internal pressure to 'build a decent stack' for day two.

Any advice would be much appreciated.

Thanks

Stack goals

Would you guys say it's best to play aggressive early out to build a stack or conservative and tight wait for best spots and does the master plan should it be any different if you had only one bullet for a tournament other then multiple bullets