Applying a systemic weed killer now?

I have a lot of a creeping weed called ground ivy (amongst other names) that grows and roots in every nook and cranny in my garden. It is difficult to kill and needs a systemic weed killer which I have in the shed. Is it pointless spraying it now or should I just hoick out as much as I can.

It's a bit late now, Goosey, the stuff hasn't any juice to work on so as Snows says, give it a seeing to with both hands, and when it tries again in the spring, ZAP it!

It has grown quite a lot since I last removed a load of it so will give a patch a spray and see how it goes but , as said, it will be more effective in the spring.