I don't bother with creep feed, I bought it in once and the lambs wouldn't eat it, complete waste of money at the time as all they wanted was grass. Our pasture is very diverse in plant and grass varieties and we're not densely stocked so they were probably getting everything they needed already. We use permaculture on our holding so policy is to nurture the soil and pasture and let nature do the rest; regular stock moves (weekly); don't pulverise the grass and encourage it's growth; regular manuring from the animals.
Since seeing how much better mothered lambs thrive compared with bottled I've tried to mimic the natural feeding patterns when bottling. It's a tall order, as it would normally be on-demand and limited by the ewes tolerance levels, but I try to as closely as practically possible by feeding lots of small feeds (including at night) in the first week or so, then gradually reducing them as the weeks go by. I eke out the last of the milk as small evening feeds for a few extra weeks as mothered lambs still steal a suck if the ewe will stand for it. I believe this also gets more milk into them, little and often, without stretching the stomachs and making them pot bellied so they have better eating patterns as adults, less prone to bloat etc.
I'm not rubbishing creep feed and other methods, just saying what works for me in case someone else finds it useful, I do get top prices when I sell them at mart so it has some validity.... downside is it is labour intensive.