That’s enough. You need 500 DPS to reinforce the structure. It will take some time given how far you are from the DPS cap of 5000.
If it is defended, that will be another matter but you should be able to grind it down with three if abandoned. I would suggest to go with something much cheaper though than T3 cruisers and fit it all gank. Something like attack battlecruisers such as the Talos or the Oracle which can put out easily more than 1000 DPS and make your grind faster with much less risk.