Being an entrepreneur is more often than not, exhausting,taxing, time consuming and drains a person physically, mentally and more importantly financially.

The answer to the question "At what point do entrepreneurs involve help, given the fact that there is no revenue yet?", in your case depends on a variety of factors.

Since you're launching a skin care product online, I'm assuming that you're either manufacturing the product yourself or you've already outsourced this function. Now, that being taken care of, there are other more important things you will have to focus on, which are pretty broad, but are things which came to mind;

1.Figuring out which e-commerce sites are the best to sell your product on.
2.Setting up your banking/payments option and getting distribution in place(Tying up with online vendors).
3.Creating your brand(Logo, creatives, product images, sample videos, marketing strategy,etc).
4. In case you're planning to create your own website and push product on that, you'll need to allocate a budget accordingly for the type of website you want and get someone to build it out for you. (WordPress is a good option). (Hiring in-house is a good option as building a WordPress e-commerce site is a fairly simple and fast solution). The other advantage is that you can mange the website yourself by watching quick tutorials on YouTube.
5. You'll need to set up a customer service/support system to take care of instances where customers return the product, dealing with bad customer reviews, you'll need someone to essentially be your PR team.
6. You will need to handle operations on a day-to-day basis and overlook your affairs in totality.

While you're at a nascent stage and you can manage these broad functions, there are essential functions which you need to focus your efforts on 100% and the rest are things which can be outsourced or in-sourced (The categorization of essential and non-essential functions needs to be done by you).

You should ideally outsource or in-source those functions which you can oversee broadly but can't get involved in on a daily basis because it cuts into your vital roles and responsibilities. Personally, it's better to hire in-house and get someone to execute your decisions, rather than outsource entire functions, because again, this becomes more expensive and you will have no control over the function, as most agencies who take outsourced work will have a number of clients and unless you constantly prioritize your work by following up, chances are that things won't get done.

Stuff like building a website, managing social media, handling operations, dealing with customer support, etc can all be done by hiring 1 or 2 competent people in-house. Competent people can be taught what to do and will charge significantly less than those individuals who hold a degree or qualification. If you're worried about burning cash, offer them equity in the business rather than making huge payments to highly qualified individuals(at least at this nascent stage) because you're not yet sure whether you'll succeed or fail w.r.t. your venture. Spend money on things which will help your business grow. Don't follow the approach big conglomerates take because you're just starting out. Your sole objectives should be to firstly survive in the market and then subsequently thrive.

You should focus on ensuring that your product has visibility, creating more channels of sale, figuring out how to get distribution in place for the offline, retail space, making sure cash flow comes in, etc. You are the glue that holds your business together, outsource/in-source any function which you feel is cutting into your time but not necessarily resulting in a productive outcome.

Hope this helps.

Cheers!