Goat kids need Lamlac at less of a concentration than lambs - it should say on the bag how much powder per ltr of water. Or google will know, I haven't fed Lamlac to goats before, I prefer Caprilac if I need to (much more expensive though).
My goat kids start off on 4 bottles a day ( after first 4 days on the dam), first two weeks as much as they take within 10 to 15 mins (warm), and they normally get to a full bottle by two to three weeks (GG's a bit less), then they are on 4 x 500ml (6am, 12noon, 6pm, 10 -11pm) plus they get offered calf mix, oats, readigrass and hay. At 12 weeks old I change to three feeds per day (usually leave out the lunchtime feed and offer concentrates etc instead), then drop a feed per month of age until 6 months, and then continue to give 10pm feed of milk as long as I have milk (and can be bothered dealing with rather rough kids by then - teats get bitten off etc). I always feed the milk warm to the touch (like you check for human babies - on your wrist)
I would think that if the kids are keen on concentrates and hay etc by 6 to 8 weeks old you can drop a feed or so earlier, lots of people wean abruptly at 12 weeks old. Given that Lamlac is not a cheap way of rearing kids, I would definitely wean earlier, but do it gradually. I wouldn't buy a new large bag of Lamlac by the time they are 3 months old.
Do you now if your kids' dams were booster vaccinated with Lambivac and/or Ovipast? If not you will need to start the vaccination at three weeks old (2 doses at 4 weeks apart), if you know that they have - then 8 to 10 weeks is advised.