You could check the pronunciation in most English dictionaries. Online you could try en.wiktionary.org. If you learn IPA (the International Phonetic Alphabet) you would be able to see how to pronounce the words as they are written in the dictionary.
After that you really just need to remember them because as you know, nothing is easy about English pronunciation. There are no hard and fast rules as English is not written phonetically.
This is how to pronounce them (using IPA)
early/ˈɜːli/ - the "r" sound is dropped in British English RP
It's interesting to note that both words beginning with E have completely different vowel sounds as do both words beginning with A.