Hello. I hope you are doing fine. Well, there is no magic number in this. You can always plan for the next baby. As long as you are healthy and sound you can try for it. Talk to your husband and mutually decide it. There is no harm in trying now or later. It depends on the couples how they go for it. Woman who are just house wives complete their families soon. On the other hand, those who are in some profession might take a little longer. They are involved in the other professional tasks too which need proper attention. If you think you can manage you time for both the babies you should go for it. Remember, the eighteen months old baby should not get ignored. Don’t neglect him with the arrival of the new. All the very best to you. Stay blessed.