If you look at the bitcoin market in October in the past years, it can be understood that it was always positive, but no one can say whether this October will be positive or negative. But OP, if you have a desire and have enough opportunities to invest, you can invest in early October.
OP can invest any time he has the funds ready to invest since plans to hodli for long, because if he relents investing because of the current price of bitcoin, he might use the monsy for something else when an emergency arises. This is one of the reason why DCA investment strategy is the best because you buy irrespective of the price of bitcoin at that moment. Whoever tells you to wait for bitcoin price to dip before buying will deprive you from owning your bitcoin now. You can only give account of today and not tomorrow.