It's not as simple as all that reallly. My post was just to provide a simple explanation. I'm not sure what you mean be muscle occupying the spaces but one adaptations doesn't really take place exclusively of the other and it also depends on intensity. None of this really matters too much in terms of what we need to know in the gym. I don't think it's possible to put exact numbers on this but it's something like 1-2 months: mostly neural adaptations and then after that a mixture of muscle growth and nerural adaptations. At some point adaptations will be most all musclular. This could be off and it is not to be taken as some kind exact rule.
Just from personal experience I can tell you that I have lost plenty of strength with little or no loss in muscle mass in the past. I always have a pretty low bf% and I can assure you that fat did not fill in anything
unless you count my lower belly. Also I would point out that what a lot of people mistake for flab is actually muslce that has lost it's "tone" with maybe some overlying subcutaneous fat. This loss of "tone" goes hand in hand with that loss of neural gains that I spoke of. But who loses muscle and who doesn't in any particular time frame depends on the person. Also the type of hypertrophy predominating I supposed could play a role.
If you're intersested in this type of thing I think there is some extra reading I could track down later.