I opened four 0%-APR-for-15 months cards with varying welcome and cashback incentives for our direct purchase last year. I paid them all off about 12 months later, but in the time in between my credit dropped 100 points due to the debt load I was carrying

It went back to normal ~4-6 weeks after paying them all off iirc.
We had 3 separate contracts and split the payments into 4 installments across 90 days, which allowed me to use so many different CC options during the
DVC payment process. In retrospect, I wish I'd thought to have my husband open up all the same new cards that I did so we could've doubled our welcome bonuses