Leave it in that pot as long as it doesn't increase in size more than 50 and don't fertilize it until planted. If it looks like it will double in size before planting,put it in a larger pot. I wouldn't remove anything. Nurseries often up-pot left overs and some set fruit before they are sold.

Here - because of our late to start and short growing season (not safe to plant out toms until end of May/beginning of June), tomato plants sold at nurseries here are almost always sold in gallon sized containers, often with flowers and fruit present.

I would disagree about not fertilizing. Depriving it of nutrients - there are virtually none in container potting soil - will stress the plant and weaken it, making it more vulnerable to pests and diseases and at a disadvantage when you can finally plant out. I would use a dilute liquid fertilizer once a week or with every other watering.

You don't say where you are located but I would try to get the plant in the ground as soon as possible. Using something like a cloche or wall of waters will guard against cold overnight temps (to some degree) as well as heating up soil temps. If you can't get it outside soon, make sure you give it as much light as you possibly can to prevent etiolation and keeping in a cooler location can also help to slow growth and reduce the tendency to flower indoors.

btw, if your tomato is an indeterminate variety, you can pinch out any new growth to keep plant dense and more compact and with no concern for removing potential flowers and fruit.

Be sure to harden off the plant properly before planting out!!

I always pinch off the lower leaves and set the stem in the ground at twice the depth of it's size. It will root all along the stem. Yes fertilize at half or fourth the dosage.