Health insurance - waiting periods (Brussels)

My husband and I are currently considering the choices regarding mutualites.

We were advised by Partena that their (additional/complementary) hospitalisation insurance has a 6-month waiting period, with maternity having a 9-month waiting period. You pay for this cover from the date of registration, but cannot claim the cover until those periods lapse. (During that waiting period you are, however, covered for accidents).

Can anyone please advise (from experience) if there are mutualites that have a shorter waiting period for this additional hospital cover? We would prefer a shorter waiting period if possible.

Thanks in advance!