You could try to use the animation-delay property and time each ellipsis character. In this case I've put each ellipsis character in a <span class> so I can animate them separately. 
I made a demo, which isn't perfect, but it shows at least what I mean :)
The code from my example:
HTML
Loading<span class="one">.</span><span class="two">.</span><span class="three">.</span>
CSS
.one {
    opacity: 0;
    -webkit-animation: dot 1.3s infinite;
    -webkit-animation-delay: 0.0s;
    animation: dot 1.3s infinite;
    animation-delay: 0.0s;
}
.two {
    opacity: 0;
    -webkit-animation: dot 1.3s infinite;
    -webkit-animation-delay: 0.2s;
    animation: dot 1.3s infinite;
    animation-delay: 0.2s;
}
.three {
    opacity: 0;
    -webkit-animation: dot 1.3s infinite;
    -webkit-animation-delay: 0.3s;
    animation: dot 1.3s infinite;
    animation-delay: 0.3s;
}
@-webkit-keyframes dot {
    0% {
        opacity: 0;
    }
    50% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}
@keyframes dot {
    0% {
        opacity: 0;
    }
    50% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}