I understand your issue as being that the "number" in the minicart only loads after the page gallery images have loaded.
I can confirm the same behavor on my Magento 2.2.0 installation. The number of items loads at the last moment.
Besides that, I think you have some optimization to do. From central Europe, your site doesn't load fast and the pagespeed ranking is poor. Have a look at Google PageSpeed insights. Some ideas, turn on the cache, optimize your images, turn on bundling / minifying of JS and CSS (please be aware, it may break your site depending on which magento 2 version you run). You could also install the mod_pagespeed, and elaborate with their filters.