If you want some great investing advice, just listen to The Rolling Stones: You can't always get what you want, but time is on your side. 

With certain stocks, though, it's best to get more time on your side by investing early. That can especially be true when they are trading at unusual discounts. With that in mind, here are three top growth stocks you should consider buying sooner rather than later.

1. Alphabet

I think the current dynamics present once-in-a-decade buying opportunities for several stocks, and Alphabet (GOOG -2.48%) (GOOGL -2.43%) ranks at the top of the list.

The tech giant's shares are rebounding from their biggest sell-off since the Great Recession. Even though Alphabet stock has been on a roll over the past few weeks, it's still down more than 30% year to date.

Sure, advertising revenue has hit a rough patch with companies across the economy tightening their purse strings. But Alphabet has been through similar ad slumps in the past and has always roared back from them. I'm 100% confident that it will do so again.

Meanwhile, its Google Cloud business continues to hum right along. Alphabet also has other potential future growth drivers with its Waymo self-driving car technology unit and its forays into healthcare. Investors who wait to buy this great stock could come to regret their hesitation.

2. MongoDB

MongoDB (MDB -0.68%) isn't as well-known or nearly as big as Alphabet. However, I think that it's one of the best up-and-coming stocks on the market right now.

Shares of the database company are still down nearly 70% year to date. MongoDB stock has never in its history fallen that much. But the underlying business remains strong.

MongoDB's revenue soared by 53% year over year in the third quarter to nearly $304 million. Sales for its main growth engine, the Atlas cloud-based database management platform, skyrocketed by 73%. 

The biggest knock against MongoDB is that it isn't profitable yet. But I think it's just a matter of time before it gets there. Increasingly larger quantities of data are being generated every minute. Many organizations are finding that the best place to store their data is in the cloud. MongoDB has differentiated itself in the marketplace with Atlas. The future looks bright for this beaten-down stock.

3. Vertex Pharmaceuticals

Not every stock has experienced hard times in 2022. Shares of Vertex Pharmaceuticals (VRTX -0.46%) are trouncing the market with a year-to-date gain of nearly 40%.

Vertex achieved its success with its four approved cystic fibrosis drugs, and that franchise still has plenty of room to grow. Vertex believes that it can expand its reach to over 50% more patients by securing additional reimbursement deals and winning regulatory approvals for its existing cystic fibrosis drugs to be prescribed to younger age groups.

But Vertex's pipeline is the main reason to buy the biotech stock sooner rather than later. The company and its partner, CRISPR Therapeutics, should soon file for regulatory approvals for exa-cel. The gene-editing therapy holds the potential to functionally cure both transfusion-dependent beta-thalassemia and sickle cell disease.

Vertex also has three other promising late-stage programs. It's evaluating a new triple-drug cystic fibrosis combo that could be more effective than its current triple-drug megablockbuster, Trikafta. It has high hopes for non-opioid pain drug VX-548. And Inaxaplin (VX-147) targets APOL1-mediated kidney disease, an indication that affects more patients than cystic fibrosis does.

It also has a potential game-changer in early-stage development. Vertex thinks that it's on the right track to develop a cure for type 1 diabetes with its VX-880 stem cell-derived islet therapy.

The company's market cap currently stands at a little under $80 billion. But I think that Vertex could surge upward and become a $100 billion-plus biotech in a Jumpin' Jack Flash.