The exact timing depends on what you're doing.
1. Moving money to your Stockpile account. If you're moving money from your bank to your Stockpile account, it usually takes 2 to 3 business days so long as you initiate your transfer before your bank's cutoff time. If you're moving more than $10,000, it will take an extra business day because the government requires us to vet larger transactions.
2. Moving money to your bank. If you're moving money in the opposite direction, from Stockpile to your bank, it will take 3 business days so long as you initiate your transfer before 3 pm ET.
Both "moving money" timelines may be affected by any hold times your bank adds (hopefully none, but you know how some banks can be).
3. Selling stock. If you're selling stock, it takes 2 business days for the trade to settle. (Literally, that's the deadline for the buyer to "settle up" with you.) Your cash will show up in your account as "unavailable cash" the day you sell your stock, and will convert to "available cash" 2 business days later. This is an industry rule called "T+2."
Wanna impress your friends with more about T+2? Check this out, straight from the source — the SEC's website: