How to quickly set anchor point to top left corner of text box?

Turning on Snapping works and selecting the Pan Behind tool (y) should work. Check your Toolbar.

Unfortunately, the first letter of a line of text is not always as tall as the rest of the letters. The Arial Black lower case "h" is taller than the Arial Black upper case "T" so the anchor point will not be at the top left corner of the word "The" if your font choice is Arial Black.

Rather than taking the time to snap the Anchor Point to the top left corner of all text layers, you could add this expression to any text layer's Anchor Point and then save it as an animation preset.

box = sourceRectAtTime();
[box.left, box.top];

 If you want the starting position to be [300 300], then adding this expression to Position and the Animation Preset would set the default position for any text layer with the pair of expressions to [300 300], and you could then manually add keyframes to the text layer.

strt = [300, 300]; // Starting Position
cCntr = [thisComp.width/2, thisComp.height/2];
value + strt - cCntr;

An even better solution would be to use an expression based on layer inPoint to create the animation. This expression would move a layer from the starting point of [300, 300] and center the text layer at the comp center. The layer would remain at the starting position (dly) for 20 frames, and then it would move to the comp center over the next 40 frames. 

s = time - inPoint;
t = s / thisComp.frameDuration;
dly = 20;
tMin = inPoint + dly; ; // tex frame delay
tMax = 40 + dly; // 25 frame move
box = sourceRectAtTime();
txtSize = [box.width/2, box.height];
value1 = [300, 300];
value2 = [960, 540] + [box.left, box.top] - txtSize;
ease(t, tMin, tMax, value1, value2);

Maybe that will get you started.