As Farmer Dan says, it may depend on the formulation. The label has wait time recommendations for soybeans and maybe a couple other crops, but I'd reconsider your approach.
I've had big issues with marestail and have learned a lot. First, it laughs at glyphosate. 24D only provides partial control and is pretty ineffective unless the plants are young. So, it is best used in the spring.
I had been planting RR beans with a light mix of corn for summer when we got the marestail infestation from a controlled burn in recently thinned pines nearby. I started by mowing in the fall after it flowered but before it went to seed. If you mow too early, it will simply regrow and flower again. It can grow from both seed and from the root system of last years plants. Mowing at the right time really helps with the seed issue, unless, like me, you have plants you can't mow growing in the nearby pines that are producing seed.
I then waited the amount of time recommended on the label for soybeans and planted a thick stand of buckwheat. Buckwheat likes warm soil and can be planted quite late, so the wait time is not an issue. Using gly on RR crops makes things worse as it kills good weeds favoring the marestail that is naturally resistant. The buckwheat comes up quickly and acts as a smother crop competing well with the marestail.
I found that using a generic version of liberty was quite effective at killing marestail and required no wait period. There is a thread on here where Bill, who plants using liberty-link, said he had no wait period for non-liberty link crops, so I tried it and it worked well. I now use liberty instead of gly for burn down.
I planted my normal fall mix which is WR/CC/PTT. Marestail was not an issue in the fall.
I have become weed tolerant over the years as many weeds are as good or better deer food than the crops we plant, but some weeds like marestail are problematic and need to be addressed. I now have a healthy mix of weeds in my summer plots. I have not gone back to soybeans. Instead, I added sunn hemp to the buckwheat for my summer stress period. It seems to be working well. I still have a little marestail, but it is now a minor weed in my fields not that I stopped using gly.
Thanks,
Jack