First Sweet Stout suggestions

Going to make my first 5 gal. batch of Milk Stout tomorrow. This is an extract recipe pretty much from 'Brewing Classic Styles' Wondering if anyone had any tips or suggestions. I'll be doing a 4 gal. boil using

.5 lb Briess Choco Malt (steeped 30 min)
.75 lb 80L Crystal (steeped)
1 lb Briess Black Patent (steeped)

7 lb Briess Light LME
1 lb Lactose

2oz Kent Goldings (60min)

Safale S-04 dry yeast

I guess the only question I really have is when do you normally add the lactose in the boil?

Be careful not to steep those grains too hot or too long, you can get more bitterness and astringency than you are looking for.
You can add the lactose late, last 15 minutes is plenty. Beware boilovers when you add it.

I usually steep the grains for about 30mins at 160F. I am going to be very wary of a boilover, I'm doing 4 gal. in a 5 gal. kettle. I wanted to up to a 10 gal kettle today, but couldn't find one locally.

I add the lactose at the end of the boil, also, just long enough to sanitize it.

+1 on end of boil lactose addition. Lactose is key.