Hi R.~ I am so happy I came across your post, because I actually help prep parents to go to India many times. Congratulations on taking your baby to such an amazing place.
Let's first deal with your formula issue once you are there. Yes, you have to take your formula with you. You have to take it in your checked luggage and it will be fine. Pack POWDERED formula. The powdered formula is okay with the temperature changes; the problem is with the liquid ready to feed. So pack powdered formula only. Please be careful and pack enough formula to last the entire duration of your trip. Many parents forget that the amount of formula the baby takes in increases as they get older. So be sure you take more with you than baby is consuming today. Since the water has to be boiled there anyway, make sure that the water is well boiled and cooled prior to making the formula.
Now I think it is worth it to call Ross Laboratories and order on line a case of ready to feed single served bottles. (They are the 2 ounce size carried in hospitals). These bottles carry on the plane with you. It is a lot easier than mixing formula on the plane. Also a lot easier to get through TSA & Customs. They are a bit more spendy; but everyone says it was well worth it. I have had some girls take the powdered for the plane ride there and carry the ready to feed ones on the plane with them but to use them on the plane ride back because of the water issue. This allows them to only lugg enough on the plane for one-way. Remember the ready to feed will have to be carried on regardless if it is for the return flight. Dubai
Also know the formula they carry in India even though it has the same name sake, is not the same formula. The babies that use it there have guts that have adapted to it, but can give a baby from here diarrhea. It is not the same even if it was not a speciality one. So stick to what you bring. If you are stopping over in Dubai or staying there, that is the best chance of getting anything that you may need.
Even though he is older 10 months old; please be careful with the solids you introduce to him there. The food here in the US (even if it is Indian food) is a bit different. Also know that (white) rice will calm down most GI upsets in baby. It has to be the white rice and rice prior to adding the spices.
I hope this helps. Be sure to bring multiple changes of clothes for him on the plane and at least a change of shirt for yourself. Be sure to take a few bottles as they will not be abled to be washed on the plane. If your bottle comes in a disposable bag form, it may be worth it to carry those instead of bottles that need to be washed. The ones you use in India can be washed and is not a big deal of the type.
I sure hope this helps. I guess the bottom line to answer your question is..... Powdered Formula is fine to packed in your checked luggage.... Good Luck!
I am adding this based on a post that is after mine. Keep your baby on the formula even if he were to be near 12 months at the time of travel. The parents I work with have found the babies do not do well with the food and the prep in India. Each one I have had that tried to make the transition while there ended up with some sick little ones GI wise. The little gut just has not been preped for it. So stick to what baby is use to. Also be sure to bring all of the infant over the counter medication you may need. That has been helpful to them as well.... A little side bar; regardless of what your relatives say..... 10 months is too early to potty train.... Laughing Out Loud!!!! When one of my best friends got back as well as one of my patients; both traveling with a 11 month old.... Both came back saying Grandma says they should be potty trained.... I thought that was really funny and decided we were sending all of the US kids to India for potty training to take a load off us here... Have fun R. and take plenty of pictures with your family with baby... Enjoy every moment and the next time you are there baby can ride the elephant....