Asking vendors for more time to make decision

This depends. If you mean you have already contracted vendors, but you need more time making decisions about products, selections, etc. that they offer, then I would just email them letting them know you need more time to think about those decisions. I found that I did not have to make final decisions until 14 - 30 days before the wedding. However, if you mean you need more time to decide on which vendor you would like to select for your wedding, then that could be a simple email as well. You can just say thank you so much for the information. My spouse and I will be discussing it further, and we will be in touch when we make a decision. Do keep in mind though, that means anyone else can book that vendor while you are deciding. So if there is a certain vendor you are really excited about, I would try to make that decision sooner than later

One thing you could do is ask the vendor to put a soft hold on your date while you consider it. This way, if anyone else reaches out to the vendor about your date, they will come back to you to ask you to make a decision at that time. Otherwise, if no one else asks about the same date, it will be tentatively held for you while you discuss with your partner to make a decision.

It's really going to depend on what decisions you are asking them to give you more time on. If you are still trying to book a vendor then it's kind of difficult for them to give you more time because they might have other clients interested in booking the date you are planning on having your wedding. They can't forever hold a date without risking losing clients. If it's something else they might have more wiggle room, but again it will depend on what you are requesting more time for. For example if it's something time sensitive like ordering tablecloths in a certain color or style if they don't already have it then they might have to order it by a certain date to guarantee they have it in time. But if it's not time sensitive then they should be understanding.