If you like the dog or under usually better to bet it closer to game time. If you like the favorite or over there is usually no upside to waiting bet it now. This is not a hard and fast rule but is the norm to betting at the best odds. As you gain experience in this business you acquire a better feel when to place your bets in order to maximize value. No one times the market perfectly all the time no matter how long you do this.
Proper betting is more important than handicapping. You can be a great handicapper and lose money if you do not bet correctly. Betting includes issues such as timing the market, closing line value, shopping effectively, having multiple outs, money management etc.
If you are unsure about the concepts I mentioned here refer to my betting advice videos on my you tube channel Professional Sports Handicapping or contact me to address any of your specific questions.
You can be a mediocre handicapper but make a living if you bet correctly. Now combine handicapping and betting effectively and you are rolling.