Actually here’s few steps to accomplish your task. First of all If you have some amount of images which you wish to show in grid after first gallery load you can play with pagination options.
Open gallery settings. In loading options block you can find Images Amount option. This options gonna help you to define amount of the images which gallery load on first step. Load More Amount – it’s amount of the gallery images on every load more step.
If you just don’t wish to have load more options enabled set Images Amount value more then you have images in gallery. In this case all images will be loaded on the first step and you will have full grid of your images in one time.
In the case if you wish to have more images in first step but don’t need load more button you can simple hide this button.
