The 26-year old Honduran international will leave MLS club Sporting Kansas City to join the Latics once the international clearance is obtained and he cannot wait to get started under Roberto Martinez.
"We spoke and he (Martinez) told me that he has been following my progress since 2010," Espinoza told Goal.com.
"He wants me there ASAP and I will be there as soon as I am cleared to do so. His idea is for me to be a key helping player in the team and I will work hard to do it.
"My contract is for two and a half years with an option. I am holding that option and I have to be grateful and happy because that is giving me peace for the future from the beginning of the contract.
"The idea is to be in England in two weeks. We will make the contract official once the contract with the MLS is done [December 31] so I won't be working with the team this year but those two weeks will be okay to settle myself there and be ready to start."