Weddingbee boards

So first off my FI and I are paying for over half of our wedding. But our parents are helping out a bit, which we are very grateful of and completely accept the help especially since they have friends and family they want there. That and we do have some big dreams. We also already have set amounts with each parent/set of parents (mine are divorced).

So now how and when do we ask them for the money??

My idea was to ask them for smaller amounts over the time of planning so its not just a large chunk at one time. Also this way it helps with deposits. But should we set up a plan like every few months? Or do we just ask when we need it? Also my FI will speak to his parents and I will speak to mine just so no one is too uncomfortable. Thoughts?

Thanks! We spoke to our parents and they all agreed that we should let them know when we need money. So every time we sign a contract with a new vendor we will let them know how much we need. It's not super specific but it works.