Adding poultry cell or nutri drench to their water is a good idea for a little boost. I give them all a little bit via their beak and also put some in the water along with electrolytes when they first arrive as shipping is stressful. I do the same with ones I hatch myself too.
Agreed on the brooder plate. It is a lot safer than a heat lamp and I have more confidence in it. Just make sure it is low enough. ChickenChick46 did point out that shipped chickens may need a faster rewarming. You can do the heat lamp or I personally leave them in the shipping box and sit outside in the sun with them to warm up if it is a hot/sunny enough day. this is also when I dose them all with poultry cell and make sure they are all looking good.
): Raising my first batch of bantam chicks! 
