4d scan

I’ve booked a 4d scan for me and my partner to go to and invited my mum, sister along with his mum and sister but I will be 34 weeks they emailed me advising that I bring it forward a few weeks but if I bring it forward then not everyone can come, does it really make a difference if I have it done at 30 weeks or 34weeks?

I don’t really want to but should I change it?