Agree with CarbHeatIn - 1 second per knot.
But, also worth adding that there is so much guess-work involved in holds, especially the hold entry, that the most important thing is to understand the inbound turn. Learn to read the ADF needle, understand dip, and interpret what's happening as you make the turn to establish on the inbound leg of the hold. If the needle is too close to the top of RMI/RBI, stop the turn. If it's too close to the bottom of the instrument, continue the turn past your planned heading.
If you can get this turn right, then it doesn't really matter what you do on the join or how (in)accurate the wind forecast is, you'll end up in the right place.
FFF
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