I've recently converted orphan airline miles from several participating carriers to HHonors points.
American Airlines was the fastest; they mailed me coupons which I mailed to HHonors. Total time to receive HHonors points about 2 weeks from my phone call to AAdvantage to seeing the HHonors points in my account.
Next fastest was Delta. I requested mileage conversion by a mailed letter and they sent me award certificates which I mailed in-turn to HHonors. Total time about 2 1/2 to 3 weeks for processing.
My Continental miles also were posted to my account today. No paperwork required, total time about 3 weeks.
Last but not least, I'm waiting for my United Mileage Plus miles to convert into HHonors points. Over 3 weeks so far, but in fairness to United, the customer service rep I spoke with advised me to expect a 4-5 week wait to see the HHonors points in my account.