When Will The Support Order Take Effect

My husbands ex wife has filed to add an addendum to their divorce decree...at present they had shared parenting with her as residential parent with $0 support to be received or paid be either party. Although my husband would give her money to help with the 3 children she feels that is in her best interest to go to court for a support order. I understand that the money my husband paid to her is considered a "gift". MY husband is on workers comp and receives less money than his ex-wife. Is it reality to assume that she will still be awarded the normal 40% of is income? They go to court the 25th...when will the support order begin and when would the first payment be due?