“Is it the same with a tomato plant?”
As far as pinching off the first blossoms, I do it if the plant is still small (under 6”) and was stressed from being in a 4-pack and I’ve rescued it from negligent owners at a ‘garden center discount bin.’ ;)
Otherwise, for me, it depends upon the type of tomato and the length of your growing season.
How far ahead are you? My tomatoes go into the garden May 31st, at 8-10 weeks old. Are your tomatoes already in the ground? How many days is your growing season, or are your plants still in starter pots and are “tall” because they’re starved for light?
I need these facts to give you an ‘educated guess-timate,’ LOL!
I haven’t grown tomatoes in 15 years but I think the first blossoms are male and do not produce fruit. I forget how you tell but I think the female flowers have tiny fruit already.