That would depend on the necessity of such a project. There are many factors to consider, such as where or how supplies will be transported to the facility, who will work at it, what the financial benefit would be, and the technological capability to build a McDonald's on mars.

Purely for the sake of speculation, installing any specific restaurant or store facilities on mars will require at the very least human habitation on mars to be mostly self sustaining without outside support, which means some level of terraforming or sufficient habitation systems to accommodate possibly thousands of people all of whom may not be trained scientists or engineers.

The discussion is mostly scifi at this point, as we already struggle to have people survive extended stays in orbit of earth, let alone on another planet long enough to build up a population large enough to make the prospect of McDonald's supplying franchises to the supposed colony. I imagine a lot of the limiting factors will be figuring out how to grow and process enough food to not only cover basic needs but to even make a luxury product like fast food available too.

There's also the matter of considering how or why a corporation like McDonald's would hope to benefit from such a effort. I imagine after a time the McDonald's installed on mars would become it's own mars exclusive chain since it would basically be feeding only mars population habitants and using those profits to keep itself running. Similar to how McDonald's has different divisions for different countries, mars would have it's own corporate McDonalds division that would only be linked to the main earth division by copyright and company policies and safety standards, with the profit generated being owned by the specific division that produced it. Really, this could be said for any earth origin corporation that produces facilities on mars.

Really, there's no realistic timeline for such a situation to occur, and I can only give general speculative answers based on levels of technical progress in a hypothetical mars colony.

Mars is a cold radioactive desert planet with a thin atmosphere, needless to say human habitation on mars will be on the same level as trying to live exclusively in a pressurized tin can with all of your living essentials being delivered via cargo landers.

Time spent on the surface would mostly consist of maintaining systems and doing research, which by that point might be more or less limited to figuring out how to turn the mars sands into usable resources. At the current point of time, a human habitation on mars is a massively pointless endeavor that would only serve to mentally traumatize a few scientists and engineers who may or may not end up dying in a place so far from home they'll never be recovered for even a symbolic gesture of closure.

The moon might be more manageable but that's just because it's closer to earth, a moon base itself would just be a ground format space station that might eventually expand to be for use at launching and refueling craft to mars and other planets without the burden of the earth's atmosphere to account for.

In short, at least for the foreseeable future, any human habitation on the moon or mars will be minimal purpose built habitats for industrial, research, or transport purposes.

Elon musk is a tech corporation billionaire with a god complex, of course he probably thinks he's going to start the expansion of humanity into the outer solar system in a decade's time. Though, realistically he probably said such things for publicity more than anything.

Keep in mind the multiverse is still an unproven concept.

Though, it's just as likely that the universe is a recycling system of finite energy and matter that periodically forms and disperses in infinite patterns.

Imagine every single atom, particle, and unit of energy in the universe being shuffled like an incomprehensible seemingly endless deck of cards that can give rise to a new thing every time. We are one such result of that shuffle, and when this iteration dissolves back into the wide nothing it used to be something will spark another shuffle and everything starts anew but different. Maybe given enough time you will form again and again in every possible situation. Maybe you've already died many many times and the nature of existing as an organic being in this generation makes you blind to your extensive existence.

Maybe you've been anything and everything in some way, maybe you've spent time as a black hole or spread across billions of lightyears as dust. Truly we have no idea if this is the first time a universe has occurred or if the heat death will actually end it.

For the sake of our own short lifespans this pondering of the infinity of time and the incalculable numbers of all things and possibilities we are better off just existing with the now and near future being our main concerns. We all will die some day, but that doesnt mean we are deleted, maybe just scattered and waiting to be re-assembled given enough time.