Obviously this part to me will be interesting to know too , because the issues here is not just buying Bitcoin and keeping it from now to 18 years to come the security of it is paramount. Also I do believe that the Op is very much aware or has gotten some Bitcoin education to have taken this decision, The crypto space is not just about doing what other people are doing, it a matter of you understanding what you are doing and what Bitcoin is all about for you to take those decisions.
I commend the Op about the long term decision and view about Bitcoin, it really the best way to start with, and with that the Op would have no worries about the bull and bear market along the line, basically wether the price goes up today or down tomorrow until the child is 18 years.
How reasonable is it to buy bitcoin in a bull market, I understand that it is easier to do it now when the price is still near the bottom, but if the price reaches 100k or even more in a bull market, do you think it would be just as reasonable to buy?
After all, after a bull market, a bear market will come again and will again last for several years, since on average we grow for one year and fall for 3-4 years. Maybe it would be wiser to put aside savings during the bull market, and buy on the next down cycle?