Dates can be tongue twisters. Practise slowly at first. /ð/ is pronounced with the front of the tongue just touching the top teeth. Don’t stick your tongue out too far, but it must be touching your teeth. This is a voiced sound. The final sound of “twentieth”, /θ/, is pronounced exactly the same, but it is unvoiced. You can check your voicing by placing your fingers on your throat. When you voice a sound you will feel the vibration. Notice the weak vowel /ə/ in “of”. This is actually its most common pronunciation. “February” is simpler than it looks. The middle “r” is silent, and replaced with /j/, which is much easier. The “ua” reduces to /ə/. Listen to the model and practise.