There is no time limit, and you will never lose your funds. ERC20 tokens will continue operating as usual, and utilities performed through the HOLD app will continue to be available.
You can perform the swap at any time in the future without any penalty, so you can take your time and evaluate what’s best for you.
Do keep in mind, however, that you won’t be able to enjoy any of the new UTK2.0 features unless you make the switch.
More info on how to do that here.