Hood's modernization plans were already prepared

Would earlier battleship completion require earlier decisions about how to modernize Hood?

The plans were already in place. Earlier replacement ships would make it easier to carry them out.

The navy had already worked out plans for Hood's modernization, so the counterfactual does not depend on beginning that design work earlier. Earlier battleship availability changes the opportunity to withdraw her for the work. A modernized Hood is envisaged as a possible flagship in the Far East. Her status would make her an attractive ship to send there as a statement of British naval strength.