In general postpartum use of the egg is not contraindicated at all - however most people and most advice will tell you that it is ideal to wait until the first 6 weeks are over. This is not only for the involution to occur, or the pelvis to heal, of course, but is because of the lochia. The period of lochia is essentially an extended menses in that the body is ridding, through the uterus, that which it no longer needs in terms of hormones (which when no longer pregnant become toxins) and fluids. In this regard, you are welcome to read the “Moontime” practice writing if you are feeling drawn to using your jade egg sooner than 6 weeks postpartum. The main involution of the uterus takes about 10 - 16 days to fully occur - however most professionals agree that full involution takes about 6 weeks and coincides with the lochia process. What may be of aid in the process, rather than using your egg prematurely, is to consider doing regular yoni steaming - a project which concluded incredible results for postpartum steaming can be read about here online:

Once again, no one can tell you or dictate what is right for you and your body; if you are feeling the call to use the egg a month postpartum, that is for your body to determine, however be mindful that if your body is looking for some aid for the process of involution and toning of the walls, it may be wise to buy a yoni steaming set prior to beginning your practice again.