If you plan to invest in one go (which is generally not recommended, especially if you don't know exactly what you are doing and if you want to hold it for a longer time, this is called market timing) then the fees are pretty small compared to the amount of money you want to invest. Usually, it is recommended to buy it over a few days, weeks, months, to minimize the risk a little bit. Thus, you are less susceptible to the volatility of the stocks.
Usually you have to pay a one-time fee independent of how many stocks you buy. So if you buy your stocks with multiple purchases, the fees might start to matter for you.
If you don't want to look at it at all I would recommend one of the more mature platforms and just pay the fees (I use AllyInvest or ETrade).
If you care about those fees, you might want to use a platform that doesn't charge you any fees (I use Robinhood, but you might need to watch the platform now and then and see what changes they implement, since they are really you and keep changing stuff). I am sure there are a few others with free trades as well.
That is just my personal experience/opinion.