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.
The kind that they lay in and the seat bounces or vibrates, those are fine right away and great to use so you can do things and have him there in the same room....the kind like jumparoos that the baby actually jumps in it and they have to sit upright in, those the baby has to be able to hold him head up well first, maybe 4 months or so.