no brainer, shove every time , ok if no 1 calls you take the blinds but you also survive to find a situation to shove again...18 left you are now looking to chip up for the final table 99 is only getting beaten by TT+ [5 hands] the majority of the time you will be ahead if anyone calls. Playing it slow is a no no you lose to much equity imo if you get 1 caller and the small blind completes your up against 3 opponents and 99 does not play well in a 4 way pot