If you look at the definition from the dictionary you will notice that in the phonological representation (the sound representation of the word) there is a small symbol that looks like an apostrophe which is placed before the stressed syllable.
I have consulted several dictionaries and have checked the phonological representation for both US and UK pronunciarion and that little apostrophe symbol is always before the beginning of the word, meaning that the stressed syllable in sometimes is SOME, not times.
I have never heard anyone pronounce this word as some-TIMES.