You have to leave the bot running.
In my config I've set MAX_LATEST_PRICE to 500 ( default setting ).
After the bot has done 500 Cycles for the selected pair, automatically switch to BB strategy and the "We dont have enough statistics..." message disappear.
I don't know what happen if you restart the bot after the message disappear, but I think the statistics have to be racalculated every time you start a pair.
Hope this help