With your eventual purchase date so far off......what would be the benefit of getting preapproved other than finding out what your loan limits are.
We would however, strongly recommend continuing to stay in touch with your designated search location by attending open houses and following prices as they continue to adjust so that when the time is "right" for you, you will be an informed buyer.
Any "pre-approval" now wouldn't mean a thing after 6 months, and in many cases 90 days. If you are asking for a lender review and guidance so you can get approved in two years, yes by all means do this.
Your credit report should have no or few late payments, your balances on open accounts should be 1/3 or below their limits and your income and assets should be secure.
You can order a copy of your credit report from each of the agencies, Experian, Equifax & TransUnion. You are entitled to a free report every year. If you have inaccurate information reporting, you should dispute it in writing to the agency(s) reporting it. They are required to affirm or remove any issue you dispute within 30 days.
Do you know what your credit score, income and bank balances will be in two years? We all wish we did!
Also, you won't know what house price you want then either.
Hang out, keep your credit good, save money and hang on!