Lime at planting. It cannot hurt to do it sooner - but it probably wouldn't help any either. I like the lime in the upper 2" at planting, I think it has a quicker effect on that year's planting - if concentrated in the topmost layers.

I like a spring planting as well. Mow it at least 2x the first year - that will take care of the annual weeds - don't worry if you mow the brassicas off - they will rebound some - but its important not to let the annual weeds take too much nutrients and/or develop seeds in year 1 - and then you can see in Year 2 - if you need to spray the grasses or not.