Will concealer left overnight ruin the growth of my new hair?

Using concealer would not affect your transplanted hair.  Many patients use it after surgery.  If you're still concerned with growth, don't use it or contact your doctor for a follow up.

 I think to use  toppik will not be very good for your new hair especially for the first 4-5 months

2 months past your transplant there's nothing really to worry about. The only things that can ruin your new hair are the same things that would ruin your natural hair. Leaving something like toppik in your hair overnight shouldn't cause your grafts any permanent damage.

You are not going to harm your grafts 2 months after a hair transplant but in the next few months the new hairs are coming in so you want to minimize any irritation or inflammation. I would recommend washing toppik off every night to prevent unnecessary build-up of the product and prevent inflammation.  If this is not possible, just be on the lookout for pimples or pustules as the new hairs grow in.  Contact your surgeon if this occurs and increase the frequency that you shampoo.

Thank you for posting your question. Being 2 months post procedure, you should be perfectly safe. Do your best in making sure you are using an organic based product. Also make sure the skin pores are cleaned out very nicely, so once the grafts that start growing 3 to 4 months out, they don't become ingrown. Hope this helps. 

I agree that two months out from a hair transplant you should not have any issues using a concealer.  If you don't have all the growth you need from the transplant, a good permanent alternative to the concealer is scalp micropigmentation.  

At 30 days and thereafter, you can use concealers on your scalp without difficulty or worry. I tell patient never to use they while there are crusts present on the scalp

After 2 months it shouldn't affect your transplanted hairs too much. It is definitely better for your hair in general to make sure taht the pores in your scalp don't get plugged but I really don't foresee any major complications by leaving in your hair concealer products for a day or two.