OK, so we have the boat up to full speed for the conditions we are sailing in and we have spent some practice time determining the correct time to cut the sheet loose. You don't have to spend a lot of practice time - 3 or 4 tacks should do it. You want to cut the jib sheet just before the jib loses power. Additionally, the lazy trimmer has set the fairlead for the new conditions. When the power trimmer decides to cut his sheet he has to be quick about it. If he is working with a self tailer he would have removed the sheet from the tailer. If he is working with a non self tailing winch, the release is simple. Just lift the sheet straight up and it comes off. With a self tailer it is a bit trickier - you may have to spin a bit to get it off. Once he decides to let it go he has to do so.At this point the lazy trimmer has taken all the slack out of the sheet. Once the loaded trimmer cuts the sheet what normally happens is the new trimmer madly pulls in the sheet. There is no point to that. He can't take all day but he should take in the sheet smoothly in order to let the jib power up. Rushing only creates mistakes.Generally, what happens on most boats is that the old trimmer now just sits there thinking his job is done. It isn't. As soon as he cuts the sheet he becomes the tailer. After this team gets the jib in as much as possable by hand it is time to insert the winch and go for final adjustment. While the new trimmer is adjusting, the lazy trimmer now takes about 3 wraps on his winch so he is ready to go for the next tack.Adjusting the jib is just part of the tack. After the jib is set the mainsail trimmer has to make his adjustment but that is a whole other story.If you practice this a few times and develop some teamwork you will be able to tack the boat in under 30 seconds and you will not lose more than 1 knot of speed.