This is probably not going to be a popular post by those that follow etiquette. If it helps a newly planning bride though... so be it. My biggest struggle and advice to you - scrutinize your guest list. I sent out 100 invitations. I have an RSVP of 220 when I only planned for 160 (this included children of close family and friends and stragglers.)
Completely where I went wrong and my fault. Initially planned to make them very specific and send in waves. I had an A, B, C list. They were going to be specific to "J. Smith 1" or "Mr. & Mrs. Smith" with no option to add guests. The A list would have a different reply date than B, and B than C. Once I had my numbers from A, I would send B, etc. Many reasons why I didn't and I wish I had. People who I allotted 2 seats for RSVP'd with 3-5. I love kids. I have kids; but if B&G do not know your kids, why bring them? I could go on with more but have few characters left. Scrutinize the list!! Spend $ on the specific RSVP. Saves $ in other areas.