I used dreft and tide free and clear and just washed all my baby stuff I have 4 weeks to go but I also put them in drawers right away, I was told to wash all clothes especially new ones in case they shrink
I have super sensitive skin so I buy the All baby detergent Its ment for babies but I use it for everyone in the house I love it and it smells good
I use anything hypoallergenic all of my babies have sensitive skin. There are also tons of detergents that say baby on them. Dreft is one, All makes another and i think Babies R Us have one they make. I plan on washing everything after I get a dresser and the baby shower.
A couple weeks before but I wouldn't go crazy washing things especially if they're new if it doesn't fit you can return it babies don't need a lot to start, as for the detergent try dreft or tide free and clear. We have used tide without any issue and we use it for the whole family so it saves us some money