What you need is a pattern. Make the outline you want and use that pattern to mark all four corners.

Jigsaws like the average Black and Decker or similar cheap brand jigsaw often cut at an angle, which is a problem especially when cutting curved lines. It can be done, but yoiu have to watch not only the cut line but how vertical the blade is staying.

The good news is that you don't have to be dead nuts perfect. When you made your practice pieces you probably cut radii on a couple of scraps, right. Then set then on top of each other to see how you did. You can't do that with a real table top, the nearest corners are, what, 3 feet apart? Most people's "eye" just isn't that good.

You can make a template and just trace a line on all four corners. Remove the bulk of the material with a jig saw and sand to the line with a belt sander. You could also build a jig and use a router with flush trim bit.

Rockler, I think, used to sell a radius template jig. With a little help from Google you could probably find plans for one on the web. You might also try magazines like Shop Notes and Woodsmith.

Thanks for the advise. Do you have any thoughts on a finish for a tiger maple table?

A pattern and a router with a pattern following bit or collar setup.