I would sound a note of caution - all goats are susceptible to pregnancy toxeamia, even ones in good body condition right up to kidding! Been there, done that and don't want to do it again, but no guarantees I think. I split their feed in the last 6 weeks into three meals, then go to 4 (late evening snack) for the last four weeks.
As by that stage they are not milking feeding to those requirements is a bit difficult, but the GGGS has produced a series of excellent leaflets, including one on feeding the in-kid goat.
Advice on there (and I do follow that):
Maintenance ration for a GG: 225 to 350g/day (for a dry doe), then 6 weeks to kidding start feeding individually
6weeks to go: increase to 2 x 225g/day
5weeks to go: increase to 2 x 350g/day
4weeks to go: increase to 2 x 450g/day
3weeks to go: increase to 2 x 675g/day
2weeks to go: increase to 2 x 750g/day
1 week to go: increase to 2 x 800g/day or maintain at 750g per portion.
My GG's weigh in at between 45 and 50kgs, so for larger goats increase acording to their weight. My BT's are between 70 to 80kgs, so get quite a bit more.
I actually start to weight the food by 4 weeks before, and definitely when I see them not finishing it. Also the advice is not to feed additional barley, as this is in most mixes and more may create toxins (I do not feed barley)
Also have a bottle of propylene glycol (1ltr bottles from the vets, and you can get it with at least two years of Use-by-date) and a drenching gun ready, if they start being too fussy and just don't look interested in their feed - drench. It doesn't do any harm, and often they do get their appetite back. The stuff used for ewes is ok too, but not really liked by goats. Same for Calciject - if they seem stiff and don't get up, inject. Same as for ewes.
I make sure they do have other feed stuffs now as well (flaked maize, readi-grass, mine get oats, shreds anyway, I also have goat mix as well as dairy nuts), so you can deal with a doe that becomes fussy (just like humans!!!). lots of different fruits etc etc. My GG's prefer mixes to straight rations, but I think they are quite fussy and I let them get away with it...