You can do this at any time without damage. You can change almost everything in HDToolbox as long as the position, size and organisation (block size, file system) of the partition does not change.
And even then, HDToolbox warns you before it saves any destructive changes. And even the warning might be too pessimistic. If you know better what you are doing, changes causing warnings might not be destructive. E.g. changing filesystem from FFS to MuFS. Or from PFS3 to PFS3ds.
Bye,
Thomas
