11 weeks

I went to my 11 week OB appointment yesterday and we are doing the genetics screening test. My doctor told me I should find out the gender of the baby before this weekend. My sons 3 year birthday party is this weekend and we were announcing we are pregnant (to those that don't know), and now we can do a mini gender reveal also. I'm wondering if I should wait to do it, or not do it at all since it is my sons 3rd birthday party. We already bought these shirts to wear for the party to "announce". What do you guys think? Wait or go ahead and do it. Someone made the comment that my son might be upset the day isn't completely about him. But, I think he may be too young to understand and if he does, it might be a good learning opportunity to teach him it won't be about him all time time since another is coming. When we announce I'll be 11 weeks 5 days, is that too early? This is our rainbow baby also.