Too late to cut the sucker?

[StevePots]

I have a tomato plant that is about 13" tall right now. The plant has a sucker that grew out when the plant was just a few weeks old. The sucker is about halfway up the plant and about the same size as the top half of the main stem causing the plant to make a perfect Y. I can only imagine that this is going to make supporting the plant difficult. This is an indeterminate currant (smaller than cherry) tomato and I believe the plant can grow very tall as it is not weighed down by large fruit.

I heard that I should only trim suckers off the lower 1/3 of the plant. As this plant is still young I'm wondering if the removal of this sucker will harm it or not.

I'm worried that the plant can split down the Y later when the branches get heavier.

[CharlieBear]

The plant is unlikely to split at the Y if the plant is tied up properly. As for trimming suckers, generally people who do take them all off, since in the states we generally grow tomatoes as annuals instead of perennials. (people who grow determinants generally don't, while most that grow determinants do, as the blossoms the suckers produce later in the season, don't generally have enough time to end up being usable tomatoes, before the season ends) The sucker could still be cut out now, if you really want to. It depends a lot on how you plant to support the plant. Most people I know have the support system in from the time they plant the plant or soon there after. As for height of the plant, that is determined by the genes (variety) not the fruit size. Some of my "cherry" tomatoes end up smaller than many of my salad tomatoes, but there is one variety that gets very big indeed.