It all depends on your risk tolerance.
If you want to go more risky, I'd do this:In your situation, since you're looking at just at a little longer than a 2 year timeline (3 years and 8 months), I might consider starting with a more conservative stock/bond approach. Warning: This approach can lose principal value, but can also help accelerate growth as well. There is risk involved.
Perhaps start with the following until you've reached 40%-50% of your goal
30% US Stock Index fund
70% Short-term bonds
Then do this until you're at 50-60% of your goal
15% US Stock Index fund
85% Short-term bonds
Then you're within 2 years of your goal and I'd buy something like the following:
100% US 1year Tbills or a CD.
Then I'd look at my very short term options in the link below to give me some flexibility in when I use the money.
Write down your plan before you execute it so you don't do something stupid (selling low) if stocks take a downturn.
Or if you're looking for the more conservative approach:Here is a post I made specifically to address your safer options. With you're little bit longer timeline than 2 years, I'd also look at short-term Bonds as an option (realizing they can also lose value if not held to duration (usually 2 years or so)). They are discussed more down-thread in the linked topic.
Of course, all of the numbers are suggestions only, and you can fill them in however you'd like.
Good luck on your goal! I'm sure you'll achieve it! Buying your first house is always a special time!