When dealing with a headache, try boiling one cup of apple cider vinegar and one cup of water in a pot. Pour into a heat proof bowl and put on the table or other safe place that you can lean over the bowl and cover your head with a towel. Inhale the steam for a few minutes to bring some relief.
The warning on mine says not to use prior to 4 months of age. My son was in his Jolly Jumper from 3 months. The directions of use are that if they can confidently hold up their head then they are fine.
1 At around 9 months of age, babies begin to pull themselves up to a standing position. By 10 months of age, a baby should be able to grasp objects with thumb and forefinger.  By twelve months of age, most babies will be crawling and trying to walk.