Your problem as described doesn't sound like meta-gaming. It sounds like making tactics, and working together. You should encourage this! If your team can act faster than the goblin, it makes perfect sense to take it out before it can take an action.

From your comment:

I am trying to stop full conversations about what to do next in combat

To me it sounds like you feel your players are spending too much time planning out every single decision in combat, which to be fair can definitely eliminate any sense of dramatic tension.

If you want to up the pace of combat, you can put them on a time limit. Get a timer, an hourglass or something similar and tell your players they have until the sand empties to make your move. 60 seconds is usually plenty of time to make a decision, and once your players get used to it they probably won't even need the timer any more. The problem is that this might put undue pressure on a newer player, since you did mention you have some in your group.

While speed factor is certainly an option, in my experience re-rolling initiative is tedious, and can drag down the pace of the game even more, especially with new players. Not to mention, re-tracking initiative every round puts even more work on your plate as DM.

As always, talk with your players before you change anything. Make sure everyone is on the same page about what you all want out of the game. If everyone is enjoying the way things are, there may not be a problem and trying to force them to change their ways could cause them to resent you.

Another option, is to just up the tactics of your monsters! Make them flank, co-ordinate, ambush, lead players into traps, etc. Let the players feel like their planning pays off when they outsmart an equally intelligent enemy.

Your problem as described doesn't sound like meta-gaming. It sounds like making tactics, and working together. You should encourage this! If your team can act faster than the goblin, it makes perfect sense to take it out before it can take an action.

From your comment:

I am trying to stop full conversations about what to do next in combat

To me it sounds like you feel your players are spending too much time planning out every single decision in combat, which to be fair can definitely eliminate any sense of dramatic tension.

If you want to up the pace of combat, you can put them on a time limit. Get a timer, an hourglass or something similar and tell your players they have until the sand empties to make your move. 60 seconds is usually plenty of time to make a decision, and once your players get used to it they probably won't even need the timer any more. The problem is that this might put undue pressure on a newer player, since you did mention you have some in your group.

While speed factor is certainly an option, in my experience re-rolling initiative is tedious, and can drag down the pace of the game even more, especially with new players. As pointed out in the comments, messing with initiative order can have other undesired effects. Monsters or players can effectively get two turns in a row, which throws off the balance of a lot of things, such as "until start of your next turn" abilities. Not to mention, re-tracking initiative every round puts even more work on your plate as DM. It also doesn't really solve the root problem of players over-analyzing combat; it just makes things more unpredictable.

As always, talk with your players before you change anything. Make sure everyone is on the same page about what you all want out of the game. If everyone is enjoying the way things are, there may not be a problem and trying to force them to change their ways could cause them to resent you.

Another option is to just up the tactics of your monsters! Make them flank, co-ordinate, ambush, lead players into traps, etc. Let the players feel like their planning pays off when they outsmart an equally intelligent enemy.