Definitely do a website first. If you want to promote your conference, it will be easier for people to share a link to your website, rather than to your mobile

Definitely do a website first. If you want to promote your conference, it will be easier for people to share a link to your website, rather than to your mobile app. Also, everyone who can run a mobile app can visit your website, but not everyone who can visit your site (eg desktop users) can run your app. A mobile app is a great idea, but it should be a bonus feature for attendees, after you've got the website fixed. [Side note: I run a tiny website promoting a certain niche of conferences - I'm less likely to promote a mobile app in my email newsletter, because I'd feel an obligation to test your app first before linking to it & recommending it. A website is easy for me to check & verify & monitor for updates.]