Head first, straight in.

Don't trim, they will do it for you if they need to and you may do it too short etc. Leave them to it, they know what they are doing

Follow what they tell you, but it took my first one 2-3 days to feel normal again, it was very very hot here though and I was heavily pregnant too lol... But the longest thing to subside was the labia swelling... it feels kinda weird, but totally love having it all gone!
It doesn't hurt as much as you expect, and the parts that hurt the most are the parts you wouldn't expect. (The worst is across the top, along your pubic line...ow!)

Have a shower before hand, wear a panty liner if you need to, but they will give you some baby wipes things before hand to freshen up too.

Good luck!!