Most probably the weekly DCA investment is best for you and you have good budget for the same like $1400 weekly can acquire you good amount of bitcoins. I am also a DCA investor and now i have been doing it for regularly for six months but last time i managed to reach $100 week for the first time in my six months DCA journey.I am also running the thread for the same on the forum to keep the members updated about how it's going and you can check it out for reference but remember it's weekly DCA investment:

My Past six months bitcoin journey

The best part is you want to invest in bitcoin not some altcoins which will give you good profits in the long run so just be patient enough to hold for all these years and buy at dips if you get chance.The amount is big so make some wise decision and store them safely in your wallets.