Congrats with a new horse :)
I got a new horse 3 months ago, about now we have achieved some kind of trust - he lets me groom him everywhere, massage a sore leg, lead him around, and he respectfully gives me space around him.. it took 3 months. Ok, possibly could have been done faster, but every day I went to him a few times, gave a few pets, a hug, just chatted a little, watched him graze, watched him play with his friend. Every time he came up to me in the pasture he gets a pat and a few good words. He willingly comes to halter, leads fine and enjoys my company. I have never bribed him with treats, he just occasionally gets to spend quality grazing time alone with me, and sometimes I take him out of the pasture to feed as his bucket is bigger than his buddy's and the other one will steal what he doesn't finish (he needs to gain weight, the other one just needs to stay where he is).
Grooming and petting will help a lot, but also other work. I bonded with the other horse that I ride very very fast, however he is a more trusting horse to start with, but my horse is 3 yrs old and doesn't do much, and cannot even atm..
be patient, work and spend some quality time together :)