There are two main factors that affect the transaction times, the first one is the great load on Bitcoin’s network. The higher the number of transactions there are, the more it takes to process each of those transactions. Since there are a limited number of miners and a limited number of transaction possible to be processed in 1 MB, it begins to take its time once the number of transaction becomes higher.
The second factor is the transaction fee attached to the BTC transaction. The fees actually decides which transaction is prioritized more than the other. Ones with higher fees attached to them are obviously prioritized so if your transaction fee is low, chances are you’ll be picked last. This factor is extremely important because the delay usually happens because of this reason more than any other reason.
Think Wisely, Transfer Small
A wise, modern man once said to begin transfers for new addresses with small amounts divided into several transactions. This way, if there is any sort of mistake or typo, you won’t lose as much as if you’d send the whole amount. Once you begin to know the balanced transaction fee that gives you a suitable transaction time period, stick to it until it begins to change (starts to take more days) and accordingly, slightly increase your transaction fees too.