Imax1 said..Never ever , force a mast up the sleeve . It will end in tears with a broken sail pocket .
You kind of scrunch the sail to get it up there . Its a technique .
There are heaps of vids on youtube on how to do this .
Its an oldie but a goodie
It depends on the brand. I can only talk with a select few brand models, and all my masts are RDM:
Severne wave sails, all sails greater than 2012: No problem. Just shove mast down in the pocket. You won't break the pocket. Really quick and the sail material has minimal creasing.
5.5 Ezzy Cheetah, the same.
Naish wave sails (2020 and below): Shove it in, until you get to about 20cm from the top (there is a little V in the material where the mast tip gets caught), shimmy down the mast and help it through. Then shimmy back and resume downhaul.
Sailworks Hucker, Revo: Do as the video says.
In the video the host puts the sail in the ground when the sail is creased up. Don't do that. Always have the sail/mast suspended when the sail cloth is creased. If you need to walk away to do something, suspend the mast with a boom so that the creases aren't touching the ground.