Here is my experience with repotting Byblis species. The key is to keep the ENTIRE root ball intact to minimise stress to the plants.
Ideally, pots that are 4" and larger are more suitable for B. guehoi as it seems to encourage branching. Cheers!
Cuttings For the ones in the plastic cups, look out for roots on the sides of the cup. There is no need to repot immediately once roots appear but it will be a suitable time if you prefer a nice-looking pot.
For those that are in the thumb pots, look out for roots coming out of bottom.
Adult plants Although I have done it successfully several times, please bear in mind that most literature discourages growers from transplanting adult Byblis plants.
What I did was just to tip the whole pot over and later place the entire root ball into a larger pot. LFS is very suitable as a media since it remains intact when repotting.