Ordering flowers help

I’m planning to order silk or wooden flowers for my wedding both to save money and because sunflowers are hard to come by in November. I’m having around 85-95 guests so probably 10-12 tables to add flowers too. I’m not sure hire many to order to ensure i have enough for the tables and to put around the venue. I’m also going to order white and red Roses and supplement with tons of eucalyptus and baby’s breath. But how many sunflowers and roses do you guys think I should be shopping for? I’m clueless when it comes to decorating weddings so I’m not sure where else I would use flowers but I’d like to put them around the venue.