"I already have a table."
Translation:У меня уже есть стол.
The best place to put "уже" is in front of the word it refers to. У меня уже есть стол. Мне уже двадцать лет. Я уже поела. Уже пять часов. Without context, these should be the default choices. Other word orders may be possible in specific contexts, but it is too much to explain at the level of this course. Your version is not exactly wrong, but unnatural for most contexts.
Is the есть mandatory in this sort of construction, or can it sometimes/always be omitted? I thought I remembered some other sentence of the form У [somebody] есть [something] where the version without есть was given as an alternative possibility, but here У меня уже стол is not accepted.
For those struggling with уже placement!
I remember this as being directly translated as "By me already have table" ("у меня уже есть") so that i know what makes sense in english, where i should split the verb.
when constructing a sentence in english, i wouldn't say "by already me have table", so "у уже меня есть" similarly does not make any sense!
the same applies for saying "by me have already table" (у меня есть уже" because i wouldn't say it like that at all, it doesnt sound right!!
Hope this helped :)