yes, it can indeed be painful to start with.
i found holding onto a support (door frame or squat rack or something) helpful. i also found this really helpful:
I use a 5kg plate.
holding a plate in front of me with outstretched arms helps, too. I try and look through the center hole. Something about having the weight held out in front of you really helps to activate the abs and engage the hip flexors helpfully.
i guess your aim is to have a comfortable bottom position for front squat with your torso as upright as possible. one thing to make sure of (once you are comfortable in the deep squat position) is that you work on maintaining your lumbar arch / sitting into your hip flexors in that deep squat position. the lightly weighted versions seem to help a lot with that.
once the bottom position is nice and comfortable i found these really helpful:
here is a version of the exercise that you want to avoid (IMHO):
he drives it up before he descends under (which gives him more time to beat the bar). but he still fails to beat the bar. he lets the weight push him down into the bottom position rather than hitting a tight bottom position underneath the bar and having the bar land on him (which is what you need in order to learn to ride the bounce).
an important thing to note: a broomstick falls at the same speed as a bar with n amount of weight loaded on it. in other words: if you can't drop yourself faster than a broomstick you have no hope in hell of falling faster than a loaded bar.
(the issue is complicated by lifters actively pushing themselves down under the bar - but i reckon you should still be able to beat the bar. that way when you learn to push yourself under you will be Even Faster).
the broomstick is also harder to balance than a slightly loaded bar. i think this is because one tends to position the bar to compensate for mobility issues. this will bite you on the ass once you get to weights that are much heavier than you IMHO (that will off balance rather than re balance you). if you are mobile enough for things to feel smooth and effortless with a broomstick and you move weight to the positions you moved the broomstick to then that will ultimately be the most helpful. at least... that is my theory. but i don't know how many agree with that (i mean i guess you can just make minor adjustments as you add weight).