I agree with
@SquawksNibbles , it can take some time.
My brother got a 1 year old budgie last December and named him Yoshi. One thing he always did was hang around Yoshi whether he's doing homework or playing on his computer. He spoke calmly around him and kept sudden moments to a minimum.
After a couple of weeks, he also started taking some of Yoshi's favorite seeds and fed them to him individually. He simply held the seed within reach of him and waited. Sure enough, when Yoshi knew he was safe, he attempted to grab for the seed. There were times when he didn't go for it, and when that happened, my bro simply backed off and tried another time.
We waited for another month or so, and then I tried to see if he would go for seeds on my palm for a change. I approached Yoshi the same way my brother did with tbe single seeds.
These took a lot of time, but a lot of it was my brother simply hanging arpund Yoshi whenver he can. The way i see it, the goal is to get your budgie to associate you and your hand to safety. The second he begins to freak out (which I assume youd recognize by now-) back off, then try again later.
This is him now with his new friend, we just recently got them loving their new pellets
(Yoshi's the green one, yellow is Bowie)