So you got some piggies! Congratulations!!
Yes, it is an issue of time, but maybe also of technique. They must get used to
your scent; and they must get to know you as bringer of good things. They must
come to realize they are totally safe with you. Get them used to your hands in the cage, when you
clean up around them, give them hay, rearrange cage furniture,etc. Never make them feel they
are being swooped on from above. A gentle scooping action from behind when they are in a corner is
the technique many use, and they must always be fully supported -- no leaving their legs dangling or making them
feel swift travel through the air when they are looking down. Very gentle motion, fully supported and then
their bodies brought gently to your chest is the way to move with them .
That said, some piggies never get used to being picked up and must be gently lured or shooed into a moveable structure if they
are to ever be picked up. I assume yours can learn to tolerate it if their last owner often picked them up. Good luck.