2 days/week @ 2 months in a small (5 kids, about 1.75 caregivers as two were there part-day but not with perfect overlap) home-based place, stayed there 'til 3. Also used grandma care 2 days most weeks. 4 half days/week starting at age 3 (different home-based place, similarly small) with additional grandma care also. Stayed there @ age 4 but cut back to 2 half-days/week and added a more "institutional" school setting for 2 (full) days/week.
This worked really well for us. Starting DS at daycare as an infant meant there was none of the fear-of-strangers stuff because his care providers weren't strangers. He got interaction with other kids (he is an only); DH and I could both work (well, DH RE'ed when DS was 3 but I want to work...); and we stayed sane, which I, at least, would have struggled with had I been home F/T with an infant/toddler/preschooler. It's true it was a tad "lumpy" but I found that 32 hours/week of childcare (approximately the average, between paid and grandma) left me many, many hours to spend with DS. Indeed, in retrospect if I could do one thing differently, I'd have used more paid childcare for DS. We are fortunate to live in an area with good options, and he enjoyed it, and I put a lot of work into trying to get us together with other families (many of whom worked and used paid childcare) and -- it would have been easier and more effective just to use more paid childcare ourselves.
Now that DS is in elementary school, I really enjoy doing things with him that he could not do as a preschooler, and am very glad I didn't focus my energies (and reduce my earnings) to spend more time out of work when he was younger, with the thought that I'd work more when he was older. I like older better.